10 Best Drill Bits for Hard Metal (October 2026)

Most failed holes in hard metal come from the wrong bit, not the wrong drill. Standard high-speed steel loses its edge as soon as heat builds in stainless steel, cast iron or hardened bolts. The bit then glazes the surface instead of cutting, work-hardens the spot and walks off the mark. Cobalt alloys hold their hardness at higher temperatures, but they vary in grade (M35 with 5% cobalt or M42 with 8%), in point geometry, in shank design and in how many sizes you actually get. The Best Drill Bits for Hard Metal depend on which of those variables matches your material and your drill.

The short answer: the Bosch CO21B 21-Piece suits most buyers who want 8% cobalt M42 steel and a split point across a wide size range. The amoolo 10-Piece 1/4-Inch M35 suits anyone who needs many identical 1/4-inch bits for repeat drilling. The DEWALT DWA1240 14-Piece suits those who want a pilot point bit in a modular storage system. The rest of the list covers a metric M42 set, several 13-piece fractional sets, and two larger kits that run up to 1/2 inch.

TL;DR: top picks at a glance

• Best overall: the Bosch CO21B 21-Piece, M42 steel with 8% cobalt and a 135-degree split point on every bit 1/8 inch and larger.
• Best for repeat 1/4-inch holes: amoolo 10-Piece 1/4-Inch M35, ten identical 1/4-inch M35 bits with a 2-3/4 inch flute length.
• Best for pilot point starts: DEWALT DWA1240 14-Piece, cobalt alloy steel bits with a pilot point and 135-degree angle in a clear-lid case.
• Best for full size range: Drill America DWD29J-CO-PC 29-Piece, 29 bits from 1/16 to 1/2 inch in 1/64-inch steps.

Best Drill Bits for Hard Metal Comparison (October 2026)

#	Product	Best for	Alloy	Pieces	Size Range
1	Bosch CO21B 21-Piece	Stainless and titanium	M42 (8% cobalt)	21	From 1/16 in
2	amoolo 10-Piece 1/4-Inch M35	Repeat 1/4-inch holes	M35 (5% cobalt)	10	1/4 in only
3	DEWALT DWA1240 14-Piece	Pilot point starts	Cobalt alloy steel	14	Not listed
4	STROTON Metric M42 19-Piece	Metric drilling	M42 (8% cobalt)	19	1-10 mm
5	RCINDUS 15-Piece 1/4-Inch M35	Spare 1/4-inch bits	M35 (5% cobalt)	15	1/4 in only
6	Axelord 13-Piece M35	Compact fractional kit	M35 (5% cobalt)	13	1/16-1/4 in
7	Drill America DWD29J-CO-PC 29-Piece	Full size range	Cobalt (M35)	29	1/16-1/2 in
8	STROTON 13-Piece M35	Bolt and stud work	M35 (5% cobalt)	13	1/16-1/4 in
9	WildBossy 20-Piece M35	Larger hole sizes	M35 (5% cobalt)	20	1/16-1/2 in
10	KENDO 13-Piece M35	Light shop use	M35 (5% cobalt)	13	1/16-1/4 in

1. Bosch CO21B 21-Piece: Best M42 Cobalt Drill Bit Set for Stainless and Titanium

• Alloy: M42 with 8% cobalt
• Pieces: 21, starting at 1/16 inch, in a plastic case
• Point: 135-degree split point on bits 1/8 inch and larger
• Shank: Three-flat on bits 3/16 inch and larger
• Warranty: Product defects only

Pros:

• The 8% cobalt M42 alloy has a higher heat resistance than the 5% M35 steel in most other sets here, which matters when drilling stainless steel and titanium.
• Split points on every bit 1/8 inch and larger start without skating, so a center punch is not needed.
• The three-flat shank on bits 3/16 inch and larger grips the chuck better under heavy load than a round shank.
• A thick web and helix design adds stability in tough applications, and the sizes include duplicates of the small bits that break most often.

Cons:

• Bits smaller than 1/8 inch do not have a split point, so tiny pilot holes need a steadier start.
• The warranty covers product defects only, which does not help with bits broken through misuse.
• The case is plastic, so it is less sturdy than the metal index boxes on some other sets.

Best for: A fabricator or serious DIYer who regularly drills stainless steel, cast iron or titanium and wants a wide set of sizes in one case.

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What sets the Bosch apart is the alloy. The Bosch CO21B 21-Piece is one of only two M42 sets in this list, and the 8% cobalt content is the reason it ranks first for the toughest materials. The surface-hardened tip penetrates abrasive stock, and the high-heat resistance suits longer cuts where an M35 bit would soften. The set also includes pairs of the common small sizes (1/16, 5/64, 1/8 and 3/16 inch), which is a practical touch for anyone who snaps the thin ones.

Against the STROTON Metric M42 19-Piece, the Bosch has the same 8% cobalt grade but uses inch sizes and adds three-flat shanks and a case. Against the Drill America DWD29J-CO-PC 29-Piece, it gives up some size coverage in exchange for the higher alloy grade. It also comes with split points on the larger bits as standard.

It is the wrong choice if you only need one hole size repeatedly. In that case the amoolo 10-Piece 1/4-Inch M35 gives you ten bits of the same size instead of a spread you will not use. It is also not the pick if your project plans are metric: the STROTON Metric set is the fit there.

2. amoolo 10-Piece 1/4-Inch M35: Best Multi-Pack Cobalt Drill Bit for Repeat 1/4-Inch Holes

• Alloy: M35 high speed steel with 5% cobalt
• Pieces: 10 bits, all 1/4 inch (6.35 mm)
• Flute length: 2-3/4 inches (69.85 mm)
• Point: 135-degree split point, uncoated, round shank
• Weight: 1.6 ounces for the full pack

Pros:

• Ten identical 1/4-inch bits mean a broken or dulled bit is a quick swap, not a stalled project.
• The 135-degree split point prevents walking and does not need a center punch.
• The fully ground spiral groove is designed to clear chips quickly, which reduces friction and heat.
• The 2-3/4 inch flute length reaches deeper than a short stub bit, and the 90-day refund or replacement policy covers dissatisfaction.

Cons:

• Only one diameter is included, so it cannot replace a general-purpose set.
• No storage case is described, so the bits need a separate organizer.
• The M35 alloy has a lower cobalt content than the M42 sets from Bosch and STROTON.

Best for: A maintenance technician or builder who drills many 1/4-inch holes in stainless steel, cast iron or steel plate.

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The amoolo 10-Piece 1/4-Inch M35 is a consumable pack, not a kit. For production work, such as a row of 1/4-inch holes in angle iron, the economics favor having ten of the same bit. The M35 alloy is a clear step up from plain HSS, and the split point and fully ground flutes cover the basics of starting accurately on hard surfaces.

The RCINDUS 15-Piece 1/4-Inch M35 is the direct rival: it offers five more bits and a plastic case. The amoolo gives up that case and that count. A buyer who cares about neat storage should look at RCINDUS, while one who wants a well-documented flute length and a clear refund policy will find amoolo straightforward. If you need more than one diameter, the Axelord 13-Piece M35 or Bosch CO21B 21-Piece is the better choice.

3. DEWALT DWA1240 14-Piece: Best Pilot Point Cobalt Drill Bit Set for Organized Toolboxes

• Alloy: Cobalt alloy steel
• Pieces: 14
• Point: Pilot point, 135-degree cutting angle, straight shank
• Case: Clear-lid, clip-latch case with a bit-bar design
• Weight: 362 g (about 0.8 pounds)

Pros:

• The pilot point design is aimed at accurate starts without a center punch.
• The patented bit-bar lets you remove individual bits easily and place them where you like.
• The clear lid shows the contents at a glance, and the clip latch closes securely.
• The compact case fits inside the Small and Medium ToughCase+ systems (sold separately), which suits a DEWALT-based tool kit.

Cons:

• The cobalt percentage and the exact bit sizes are not specified.
• The set has fewer pieces than the Bosch and the larger Drill America and WildBossy kits.
• The shank is straight, so it does not have the added grip of the three-flat designs.

Best for: A DEWALT toolbox user who values organized storage and quick, accurate starts on stainless steel and alloy steel.

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The DEWALT DWA1240 14-Piece is as much about the storage system as the bits. The connectable case and bit-bar are the main differentiators, and the cobalt alloy steel is recommended for stainless steel, alloy steel and iron. A 3 mm minimum bore diameter shows the set starts at small sizes.

Compared with the Bosch CO21B 21-Piece, the DEWALT is the more organized option but a less documented one, since Bosch states its 8% cobalt content and shank design. Compared with the Axelord 13-Piece M35, the DEWALT offers a more modular case but without a stated alloy grade.

It is the wrong choice if you need a confirmed cobalt percentage or a known size list before buying. The Drill America DWD29J-CO-PC 29-Piece states its range from 1/16 to 1/2 inch, and the Bosch states its M42 grade.

4. STROTON Metric M42 19-Piece: Best 8% Cobalt Metric Drill Bit Set for Stainless Steel

• Alloy: M42 with 8% cobalt, 68-70 HRC
• Pieces: 19, from 1 mm to 10 mm in 0.5 mm steps
• Point: 135-degree split point, straight shank
• Flutes: Two, hardened finish
• Weight: 16 ounces

Pros:

• The 8% cobalt M42 steel at 68-70 HRC is the same grade class as the Bosch.
• Half-millimeter steps from 1 mm to 10 mm cover most metric clearance and tap-drill sizes.
• The 135-degree split point reduces walking on hard stock.
• Bit lengths scale with diameter, from about 3.4 cm for the 1 mm bit to 13 cm for the 10 mm bit, which gives reach on the larger sizes.

Cons:

• No case or storage is described, so the bits need an organizer.
• Sizes are metric only, which is awkward for inch-based fastener work.
• The straight shank has less grip than a three-flat design at the larger sizes.

Best for: A machinist or hobbyist working to metric drawings on stainless steel and other hard alloys.

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The STROTON Metric M42 19-Piece is the metric counterpart to the Bosch. It has the same high cobalt content but a finer step between sizes, and the 0.5 mm increments are useful for tap drilling and fitted holes.

The STROTON 13-Piece M35 is from the same brand but is inch-based with lower cobalt content and a case, so choose by measurement system first. If you work in inches, the Bosch is the better M42 option. This set is the wrong one for anyone who wants a ready-to-carry kit, since no case is described.

5. RCINDUS 15-Piece 1/4-Inch M35: Best Spare-Pack Cobalt Drill Bit for 1/4-Inch Hardened Stock

• Alloy: M35 high speed steel with 5% cobalt
• Pieces: 15 bits, all 1/4 inch (6.35 mm)
• Point: 135-degree split point, straight shank, uncoated
• Flutes: Two
• Accuracy: Diameter controlled within -0.03 mm

Pros:

• Fifteen 1/4-inch bits give the largest spare count of the single-size packs.
• A plastic storage case keeps the bits together.
• The self-centering split point prevents walking on hard surfaces.
• Buyer feedback highlights sharpness and versatility, including success in hardened stainless steel.

Cons:

• Only one diameter is included.
• The uncoated finish offers less surface protection than the black oxide, titanium or gold finishes on other sets.
• M35 is a lower grade than the M42 in the Bosch.

Best for: A user who drills a large number of 1/4-inch holes across steel, stainless steel, plastic and wood.

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The RCINDUS 15-Piece 1/4-Inch M35 is a refill option. Its quality and value feedback is positive, and it handles wood, plastic and soft metals as well as hard stock, which makes it versatile for a shop that drills mixed materials.

Compared with the amoolo 10-Piece 1/4-Inch M35, it has more bits and a case. It is the wrong choice if your jobs need several sizes: the Axelord 13-Piece M35 covers 1/16 to 1/4 inch with an index case.

6. Axelord 13-Piece M35: Best Compact Fractional Cobalt Drill Bit Set for Everyday Hard Metal

• Alloy: M35 high speed steel with 5% cobalt
• Pieces: 13, from 1/16 to 1/4 inch in 64ths
• Point: 135-degree split point
• Flute: Parabolic, two flutes
• Finish: Black oxide, straight shank

Pros:

• All thirteen sizes from 1/16 to 1/4 inch are included, covering typical pilot and clearance holes.
• The parabolic flute is designed for smooth chip removal.
• Black oxide finish adds some surface protection.
• An index case keeps sizes organized, and a 30-day money-back guarantee is offered.

Cons:

• The set stops at 1/4 inch, so larger holes need a step bit or a bigger set.
• A straight shank has less grip than the three-flat shanks on the Bosch.
• It uses M35 cobalt, not M42.

Best for: A homeowner or hobbyist who needs a tidy small-size set for stainless steel, cast iron and hard plastics.

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The Axelord 13-Piece M35 is a typical small cobalt kit with the distinctive parabolic flute. That flute geometry is the main feature separating it from the spiral-flute STROTON 13-Piece M35 and KENDO 13-Piece M35, which have the same size range.

It is the wrong choice if you need holes larger than 1/4 inch. The WildBossy 20-Piece M35 and Drill America DWD29J-CO-PC 29-Piece both go up to 1/2 inch.

7. Drill America DWD29J-CO-PC 29-Piece: Best Full-Range Cobalt Drill Bit Set for Shop Benches

• Alloy: Cobalt steel (M35)
• Pieces: 29, from 1/16 to 1/2 inch in 1/64-inch steps
• Point: 135-degree self-centering split point
• Finish: Gold oxide, round shank
• Weight: 2.2 pounds, round case

Pros:

• Every 1/64-inch step from 1/16 to 1/2 inch is included, the finest size coverage in this list.
• The gold oxide finish lubricates the bit and adds wear resistance.
• The split point is designed to penetrate hard material without a pilot hole and produces small chips to reduce clogging.
• The set meets ANSI specifications, and buyer feedback is positive on sharpness and the storage case.

Cons:

• Durability feedback is mixed, with some reports of breakage on first use.
• Round shanks do not have the extra grip of three-flat designs on the larger bits.
• At 2.2 pounds, the case is heavier than the compact 13-piece sets.

Best for: A workshop that drills a broad range of fractional sizes in steel and stainless steel, often on a drill press.

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The Drill America DWD29J-CO-PC 29-Piece is the size-range pick. Full 1/64 steps make it useful when a hole needs to match a specific fastener or reamer allowance. Buyer feedback links it to drill press use and describes cutting performance in steel as strong.

Compared with the WildBossy 20-Piece M35, it covers more sizes and has an ANSI-conforming build. Compared with the Bosch CO21B 21-Piece, it has more sizes but a lower cobalt content. It is the wrong choice for field work where weight matters, or if you want the highest heat resistance: the Bosch is better.

8. STROTON 13-Piece M35: Best Three-Flat Shank Cobalt Drill Bit Set for Bolts and Studs

• Alloy: M35 high speed steel with 5% cobalt, 68 HRC
• Pieces: 13, from 1/16 to 1/4 inch in 1/64-inch steps
• Shank: Three-flat
• Flutes: Two, hardened finish, 135-degree angle
• Case size: 7 x 3 x 0.69 inches

Pros:

• The three-flat shank grips the chuck better than the round shanks on the Axelord and KENDO sets.
• The set is marketed for heavy-duty work including cast iron, steel plate and drilling out bolts, studs and screws.
• The hardened 68 HRC steel is intended to resist heat and wear.
• The compact case measures 7 x 3 x 0.69 inches and fits in a toolbox drawer.

Cons:

• The point style is only described as "point", so the split point is less clearly specified than on competing sets.
• It stops at 1/4 inch.
• The same M35 grade as the cheaper-looking sets here, with no extra alloy advantage.

Best for: A mechanic who drills out seized fasteners and needs grippy shanks in small sizes.

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The STROTON 13-Piece M35 is similar to the Axelord and KENDO on paper, but the shank is what differs. Slip is a common issue with small bits under torque, and the three-flat shank is a sensible answer.

Pick the Axelord 13-Piece M35 instead if you want a clearly stated 135-degree split point and a parabolic flute. Pick the Bosch CO21B 21-Piece if you want higher cobalt and more sizes.

9. WildBossy 20-Piece M35: Best Titanium-Finish Cobalt Drill Bit Set for Larger Holes

• Alloy: M35 cobalt steel, up to 67 HRC
• Pieces: 20, from 1/16 to 1/2 inch, with pairs of the small sizes
• Point: 135-degree split point
• Finish: Titanium, with a three-flat shank
• Weight: 15.2 ounces, plastic storage case

Pros:

• The 20 pieces reach 1/2 inch, with 5/16, 3/8 and 1/2 inch bits that most 13-piece sets lack.
• Pairs of 1/16, 5/64, 3/32, 7/64, 1/8 and 3/16 inch bits cover the sizes most likely to snap.
• The titanium finish and three-flat shank add surface protection and grip.
• Buyer feedback includes success on heavy steel plate and drilling into snapped bolts.

Cons:

• Buyer feedback on sharpness and durability is mixed, with reports of quick dulling and breakage.
• The 9/64, 5/32, 11/64, 7/32 and 1/4 inch sizes come as single bits.
• The product is not suitable for glass or ceramic.

Best for: A DIYer who wants larger sizes up to 1/2 inch in a compact case.

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The WildBossy 20-Piece M35 sits between the 13-piece sets and the 29-piece Drill America kit. It reaches the same 1/2 inch top size but with fewer sizes and a lighter case.

Because the feedback is mixed, it is a weaker choice for demanding stainless work, where the Bosch CO21B 21-Piece is the safer pick. Use lubrication and control speed, pressure and heat, as the product notes advise.

10. KENDO 13-Piece M35: Best Bronze-Finish Cobalt Drill Bit Set for Light Shop Use

• Alloy: M35 high speed steel with 5% cobalt
• Pieces: 13, from 1/16 to 1/4 inch in 64ths
• Point: 135-degree self-centering split point
• Finish: Bronze steam treatment, straight shank
• Case: Metal box with size index, 5.71 x 3.39 x 0.71 inches

Pros:

• The metal box with a size index is sturdier than the plastic cases on several other sets.
• A thick web design strengthens the core and flute.
• The self-centering split point reduces thrust and helps start cuts.
• The set is positioned for stainless steel, cast iron, high-temperature alloy and titanium alloy.

Cons:

• Durability feedback is mixed, with some reports of bits breaking too easily.
• It tops out at 1/4 inch.
• Flute type is described inconsistently, so check the bits on arrival.

Best for: An occasional user who wants a small cobalt set in a rugged metal box.

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The KENDO 13-Piece M35 is a functional small kit with a better-than-average case. Its size range matches the Axelord 13-Piece M35 and STROTON 13-Piece M35, so the differences are finish, case and shank.

It is the wrong choice for repeated production drilling or tough stainless jobs, where the Bosch CO21B 21-Piece is stronger. The mixed durability feedback suggests keeping it for lighter work.

Buyer's Guide: How to Choose the Right Drill Bit for Hard Metal

The core trade-off is between alloy grade and size coverage. Higher cobalt resists heat better but is found in fewer sets, while the broadest size ranges use the more common M35 grade.

Before choosing, check these project details:

• Material: Stainless steel, cast iron and hardened bolts demand more heat resistance than mild steel.
• Hole sizes: Count the diameters you really need, since single-size packs and full kits serve different jobs.
• Measurement system: Inch and metric sets are not interchangeable for fitted holes.
• Drill type: A drill press, a cordless drill and a hammer drill each affect bit life differently.
• Storage: Case type and index markings decide how long a set stays organized.

Cobalt Grade and Alloy

M35 steel contains about 5% cobalt and is the standard in this list, used by amoolo, RCINDUS, Axelord, STROTON, WildBossy and KENDO. M42 steel contains about 8% cobalt and offers higher heat resistance, which is why the Bosch CO21B and the STROTON Metric set lead on tough materials.

For occasional stainless steel work, M35 is adequate if you control speed and use cutting oil. For a project that is dominated by hardened plate, compare these general-purpose sets with a drill bit for drilling hardened steel, which may suit the specialist job better.

Point Geometry and Shank Type

A 135-degree split point is the standard for hard metal because it self-centers and avoids walking. The Bosch, amoolo, Drill America and WildBossy all state it, while the DEWALT uses a pilot point with the same 135-degree angle.

Shank design matters under torque. Three-flat shanks on the Bosch, STROTON 13-Piece and WildBossy grip better than the round or straight shanks on the amoolo, Axelord and KENDO. Use rotation-only mode, since the percussion of a hammer drill chips brittle cobalt tips.

Set Size and Range

Single-size packs such as the amoolo and RCINDUS suit repeat jobs. Thirteen-piece sets from Axelord, STROTON and KENDO cover 1/16 to 1/4 inch. For larger holes, WildBossy reaches 1/2 inch in 20 pieces, and Drill America reaches the same limit with 29 bits in 1/64-inch steps.

Metric users should choose the STROTON Metric set, which runs 1 to 10 mm in half-millimeter steps. A mismatched system forces you to round to the nearest size and can compromise fit.

Finish and Storage

Finishes include black oxide on the Axelord, gold oxide on the Drill America, titanium on the WildBossy and bronze on the KENDO. These reduce friction and add some wear resistance, but the alloy grade matters more than the coating.

Cases differ in practical ways. The KENDO has a metal box, the DEWALT has a modular clear-lid case, and the Drill America has a round case. Hot chips and hot bits can burn, so keep welding gloves for handling freshly drilled work, and take them off before the drill is spinning.

Frequently Asked Questions About Drill Bits for Hard Metal

Is Cobalt Better Than Titanium-Coated Drill Bits for Hard Metal?

Cobalt is generally the better choice because the alloy is hard all the way through, while a coating wears off at the surface. The Bosch CO21B and Drill America sets use cobalt steel, and the WildBossy combines M35 cobalt with a titanium finish. A coating adds some friction reduction, but the base steel matters more.

What Is the Difference Between M35 and M42 Cobalt Drill Bits?

M35 contains about 5% cobalt and M42 contains about 8%. The Bosch CO21B and STROTON Metric sets are M42, while amoolo, RCINDUS, Axelord and others are M35. M42 resists heat better, which helps in stainless steel and titanium.

Do I Need a Center Punch With These Drill Bits?

Not with the split point sets. The Bosch states that its split points eliminate the need for a center punch on bits 1/8 inch and larger, and the amoolo says the same for its 135-degree split point. The DEWALT uses a pilot point designed for accurate starts.

Which Set Is Best if I Need Bits Larger Than 1/4 Inch?

The Drill America DWD29J-CO-PC reaches 1/2 inch in 1/64-inch steps, and the WildBossy 20-Piece M35 also reaches 1/2 inch. The Bosch CO21B has a stated range that starts at 1/16 inch, but its top size is not fully specified here. The 13-piece sets and the single-size packs stop at 1/4 inch.

Can I Use Cobalt Drill Bits on Wood and Plastic?

Yes, many of these sets list wood and plastic among suitable materials, including the RCINDUS, Axelord and STROTON 13-Piece sets. They are designed for metal first, so they may be more than you need for soft materials. Control speed and pressure as the makers advise.

How Do I Make Cobalt Bits Last Longer?

Keep the speed moderate, apply steady pressure and use cutting oil to control heat. The product notes for amoolo and WildBossy both point to speed, pressure and heat control. Avoid hammer mode and replace dull bits instead of forcing them.

Final Verdict: Which Drill Bit for Hard Metal Should You Buy?

Best Drill Bits for Hard Metal for most buyers start with Bosch CO21B 21-Piece: it uses 8% cobalt M42 steel, 21 pieces from 1/16 inch, split points on bits 1/8 inch and larger, and three-flat shanks on bits 3/16 inch and larger. Its main weakness is that the warranty covers product defects only and the case is plastic.

For alternatives by use case, the amoolo 10-Piece 1/4-Inch M35 and RCINDUS 15-Piece 1/4-Inch M35 suit repeat 1/4-inch jobs, with RCINDUS adding a case. The DEWALT DWA1240 14-Piece is best for pilot point starts and modular storage. Those who work in metric should choose the STROTON Metric M42 19-Piece, and those who want broad inch coverage should choose the Drill America DWD29J-CO-PC 29-Piece.

The specialist picks fill narrower roles. The Axelord 13-Piece M35 adds a parabolic flute, the STROTON 13-Piece M35 adds three-flat shanks for bolt work, the WildBossy 20-Piece M35 reaches 1/2 inch with a titanium finish, and the KENDO 13-Piece M35 offers a metal index box. If you are still undecided, buy the Bosch and add a single-size pack only if one hole diameter dominates your work.