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Metal-drilling buying guide
Drill bits for metal: choose the set by material and tool
Start with the metal, the hole size and your tool's bit holder. Bosch CO14B is a cobalt M42 set from a family intended for hard and abrasive metals, including stainless steel. DEWALT DWA1181 is a standard HSS set for metal, wood and plastic. Makita B-65399 is expressly impact-rated for ¼-inch hex impact drivers.
Published October 7, 2026. Manufacturer pages and exact Amazon listings checked October 7. Based on published sources, not hands-on drilling or durability tests.
Three sets for different buying reasons
These are package choices, not a speed or lifespan ranking. Use the checks beside each choice before ordering. If you already have suitable bits in the required size, a larger assortment may add nothing to this job.
Match the material and tool; then confirm the exact size and shank fit.
Your requirement
Set to consider
Useful difference
Check or skip
Hard or abrasive metal, including stainless, with a rotary drill
14 titanium-nitride-coated bits expressly rated for this impact-driver connection.
¼ inch is the shank size, not the largest hole. Confirm the driver manual's accessory requirements and drilling limits.
Check the holder, the hole and the material separately
A bit that fits a drill chuck is not automatically an impact-driver bit. Bosch describes its cobalt sets for rotary drills/drivers and cylindrical shanks for three-jaw chucks. DEWALT labels DWA1181 “Standard” and describes three-flat shanks. Makita expressly states both ¼-inch hex fit and impact rating for B-65399. Choose the documented connection and intended use together.
The largest cutting diameter is not the shank diameter or your drill's material capacity. The size lists below reach ½ inch, but they do not establish that every bit fits every ⅜-inch chuck. Check the bit's actual shank against your tool's chuck range, and check the tool manual's capacity for the metal and hole you need. Makita's ¼-inch hex shank is a different measurement from its individual bit diameters.
These fractional assortments do not supply every diameter between 1/16 and ½ inch, and none lists a bit larger than ½ inch. If the required diameter is absent, select that exact accessory rather than substituting the nearest size. For masonry, a threaded hole or a job requiring another cutting system, check that task's specified accessory; these metal-bit assortments alone do not establish suitability.
For ordinary metal holes with a hammer drill, use the tool's ordinary drilling mode. Our hammer drill vs impact driver guide explains the mode and holder differences using exact tool manuals. If you need a tool as well, compare the drill and combo-kit guides; these bit sets do not include a drill, battery or charger.
What each exact set changes
Bosch CO14B: cobalt M42 for a rotary-drill setup
Bosch identifies CO14B as its 14-piece cobalt M42 set. The shared cobalt-set page describes use in hard and abrasive materials and stainless steel, a no-skate tip, and three-flat shanks on bits 3/16 inch and larger. These are Bosch's family descriptions, not drilling results we measured.
Consider it when those metal applications and a compatible three-jaw chuck match the job. Its exact contents have 13 different diameters plus a second ⅛-inch bit. The linked Amazon CO14B listing includes 14 drill bits and a case; a drill and the rest of the work setup are separate.
Skip this assortment if you need 11/64, 13/64 or 15/64 inch: those sizes are absent from its contents. Do not assume its cylindrical shanks have Makita's documented hex-impact fit or rating.
DEWALT DWA1181: more sizes and duplicates in a standard HSS set
DEWALT describes DWA1181 as 21 high-speed-steel bits for metal, wood and plastic, with black-and-gold coating, 135° split-point tips and size markings. Its footnote limits three-flat shanks to sizes larger than 3/16 inch; it does not say every bit has flats.
The exact Amazon listing supplies the size breakdown: 16 different diameters and five duplicates, for 21 bits total. It adds 11/64, 13/64 and 15/64 inch, and duplicates 1/16, 5/64, ⅛, 3/16 and ¼ inch. Choose it for those actual sizes or spares, not because 21 pieces necessarily means more suitable metal performance.
Confirm chuck fit before ordering: DEWALT's page calls it a standard set and describes three-flat shanks, but its specification table also says “Chuck Type: SDS-Plus.” The Amazon listing instead says straight shank. Those fields conflict. This guide does not recommend DWA1181 for an SDS holder or an impact driver; verify the actual shank and your drill's requirements. DEWALT's page does not provide individual shank diameters or an itemized size list.
Makita expressly rates B-65399 for ¼-inch hex impact drivers. Its 14 bits have titanium nitride (TiN) coating and 135° split-point geometry. Makita lists drilling applications in ferrous and non-ferrous metal, cast iron, stainless steel, wood and plastic; stainless use is not exclusive to the Bosch option.
Consider it when you already own a compatible impact driver and want the exact fractional sizes below. It has 13 different diameters and a second ⅛-inch bit. The maker's includes list itemizes the bits; it does not itemize a storage case. The impact driver is sold separately.
Skip it if your required size is 11/64, 13/64 or 15/64 inch, or if your tool's accessory requirements do not match. TiN coating and impact rating describe different properties; they do not establish that it outlasts or out-drills the cobalt set in your metal.
Bosch CO14B and Makita B-65399: one each of 1/16, 5/64, 3/32, 7/64, 9/64, 5/32, 3/16, 7/32, ¼, 5/16, ⅜ and ½ inch, plus two ⅛-inch bits. That is 14 bits in 13 different sizes, according to each maker's contents list.
DEWALT DWA1181: two each of 1/16, 5/64, ⅛, 3/16 and ¼ inch; one each of 3/32, 7/64, 9/64, 5/32, 11/64, 13/64, 7/32, 15/64, 5/16, ⅜ and ½ inch. That is 21 bits in 16 different sizes, from the exact Amazon listing's contents bullet. Confirm that assortment on the current listing when buying; DEWALT's product page confirms 21 pieces but does not enumerate the sizes.
Common questions
Which of these sets can I use in an impact driver?
Makita explicitly rates B-65399 for ¼-inch hex impact drivers. Bosch describes its cobalt sets for rotary drills/drivers; DEWALT calls DWA1181 Standard. Check your driver's retention and accessory requirements. Shank fit by itself does not establish impact suitability.
Does a ¼-inch hex bit only make a ¼-inch hole?
No. On Makita B-65399, ¼ inch describes the hex shank. Its included cutting diameters range from 1/16 through ½ inch, with gaps between sizes. Verify the individual diameter you need and the tool's drilling capacity.
Is cobalt always better than a titanium-coated bit?
This guide does not establish a universal winner. Bosch's CO14B is a cobalt M42 set in a family intended for hard and abrasive metals and stainless steel. Makita B-65399 has TiN coating and an explicit hex-impact rating, including a maker-listed stainless application. Choose by the metal, holder and exact size; no comparative durability test supports a lifespan ranking here.
Does the 21-piece DEWALT set have 21 different sizes?
No. The DWA1181 listing itemizes 16 different diameters with duplicates at 1/16, 5/64, ⅛, 3/16 and ¼ inch. Bosch CO14B and Makita B-65399 each have 13 different diameters and a duplicate ⅛-inch bit. Piece count includes the duplicates.
Sources and buying limits
Manufacturer pages and exact listings were checked October 7, 2026. At that check, all three selected new listings were sold by Amazon.com and showed “In Stock.” Stock, seller and package can change. The linked model is the relevant unit, not every similarly named brand set.
The Amazon links above support the exact package identities, CO14B's case and DWA1181's itemized sizes. Warranty coverage is not compared: DEWALT's checked page says warranty information is unavailable, and the Bosch and Makita product pages read here do not give model-specific accessory terms. These are limits of the sources checked, not a claim that the products have no warranty. We have not measured hole quality, drilling speed, bit life or resharpening performance.