SKU: 36471613045

Bosch CO21B 21 Piece Cobalt M42 Metal Drill Bit Set for Stainless Steel Cast Iron and Titanium High Heat Resistant 135 Degree Split Point

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Description

Bosch CO21B 21 Piece Cobalt M42 Metal Drill Bit Set for Stainless Steel Cast Iron and Titanium High Heat Resistant 135 Degree Split PointUnrivaled Durability in Hard Metals: Engineered with 8% Cobalt for 10X Longer Life The Bosch CO21B 21 Piece Cobalt M42 Drill Bit Set is the definitive choice for professionals facing the toughest drilling challenges. Engineered with an upgraded M42 alloy containing 8% cobalt, these "hard core" bits are specifically designed to deliver 10X the service life of standard bits while withstanding extreme heat in high temperature applications. Whether you

Unrivaled Durability in Hard Metals: Engineered with 8% Cobalt for 10X Longer Life

The Bosch CO21B 21-Piece Cobalt M42 Drill Bit Set is the definitive choice for professionals facing the toughest drilling challenges. Engineered with an upgraded M42 alloy containing 8% cobalt, these "hard-core" bits are specifically designed to deliver 10X the service life of standard bits while withstanding extreme heat in high-temperature applications. Whether you are drilling through stainless steel, cast iron, or titanium, the thick web-helix design provides superior stability and rapid material removal, ensuring precision and efficiency on every job.

Designed for maximum jobsite performance, these bits feature a specialized 135-degree split point on all sizes 1/8" and larger, allowing for immediate, "no-skate" starts without the need for a center punch. To further increase productivity, bits 3/16" and larger are equipped with a three-flat shank that provides a secure grip in the drill chuck, effectively eliminating bit slippage during high-torque tasks. From light-gauge aluminum to abrasive hardened metals, this comprehensive set provides the specialized tip geometry and heat resistance required for professional-grade results.

Key Features

  • Upgraded M42 Alloy: Formulated with 8% cobalt to provide 10X life versus standard drill bits.
  • Extreme Heat Resistance: Engineered to withstand high-temperature applications for extended periods without dulling.
  • Thick Web-Helix Design: Increases structural stability and provides fast material removal in tough materials.
  • No-Skate Split Point: Bits 1/8" and larger feature a split point for accurate starts without a center punch.
  • Secure Three-Flat Shank: Bits 3/16" and larger feature three flats on the shank to prevent bit slippage in the chuck.
  • Hardened Surface: Specifically designed to penetrate hardened surfaces including stainless steel, titanium, and cast iron.

What's Included

  • (2) 1/16", (2) 5/64", (1) 3/32", (1) 7/64" Cobalt Bits
  • (2) 1/8", (1) 9/64", (1) 5/32", (1) 11/64" Cobalt Bits
  • (2) 3/16", (1) 13/64", (1) 7/32", (1) 15/64" Cobalt Bits
  • (2) 1/4", (1) 5/16", (1) 3/8", (1) 1/2" Cobalt Bits
  • (1) Rugged Storage Case

Specifications

Brand Bosch
Model Number CO21B
Bit Material M42 Cobalt Alloy (8% Cobalt)
Bit Type Twist / Jobber Length
Total Piece Count 21
Tip Geometry 135-Degree Split Point
Shank Design Three-Flat (3/16" and larger)
Weight 1.19 lbs
Compatible Materials Stainless Steel, Cast Iron, Titanium, Aluminum
Product Condition New

Pro-Tip: When drilling into hard metals like stainless steel with cobalt bits, use a slower drill speed and apply steady pressure. This technique, combined with the 8% cobalt alloy, minimizes heat buildup and ensures the longest possible cutting life for your bits.

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 36471613045

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Verified Purchase
Jonas Morel
Lowell, US
★★★★★ 5
Affordable, easy to install
Size: C10 / C20 Bags
Works great :)
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 19, 2026
L
Verified Purchase
Lucia
Fort Morgan, US
★★★★★ 1
Doesn’t fit
Size: C10 / C20 Bags
Same exact things happens to me of this review — If you have an Omni C20, don't bother with these. They do not fit. The cardboard is too small and it keeps tripping the sensor that detects the bag when I put the cover back on. I've tried multiple bags in the set and they all do the same thing. Now to go find the place to report this listing for false advertising so maybe other people won't get scammed like me and others in the comments have.
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Reviewed in the United States on March 19, 2026
R
Radar
Battle Creek, US
★★★★★ 5
Replacement Roller brush for my robovac
when you have long-haired dogs... these rollers WILL get tangled up with yards of hair...and although you can (and we do) take them out...and clean them off, after a while, the design of the roller is changed because of these tangles... This replacement roller is great, easy to install, and cost effective. would recommend if for no other reason, than keeping my house cleaner
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Reviewed in the United States on April 22, 2026
L
Lyle Swann
Chelsea, US
★★★★★ 5
Fits Perfect
This fits my cordless P10 Pro perfectly. It has some foam and hard grooves for picking up debris. The part feels very solid, not cheap or low quality at all. Be sure your Dreame is one of the models listed as this only fits those. It won't fit any of the other brands that share some of the Dreame parts (like Mova, for example). The rollers do eventually wear and reduce performance. This is a nice alternative to the name brand.
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Reviewed in the United States on December 19, 2025
G
Verified Purchase
Gio Garcia
Los Angeles, US
★★★★★ 5
Good Replacement Set
Style: 19 Pack
Good replacement set for the price. Parts are basically like the originals and are easily installed for a perfect fit for the 25C.
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Reviewed in the United States on July 11, 2025

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