BOSCH CO21 Cobalt M42 21-Piece Set Review
BOSCH CO21 21-Piece Assorted Set with Included Case Cobalt Metal Drill Bit with Three-Flat Shank for Drilling Applications in Stainless Steel, Cast Iron, Titanium, Light-Gauge Metal, Aluminum
$101.90 (price as of 2026-11-07)
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Reddit score
3.6 Based on 1 Reddit owner comment · Top 50% of 4 tracked drill bit sets
| Owner sentiment | 4.2 | |
| Recommendations | 1.0 | |
| Spec score | Not rated | |
| Value | 4.2 |
How these are computed: methodology. Components without evidence show “Not rated” and their weight moves to the others.
Limited Reddit owner feedback. We need more owner experiences before this score is reliable, so this page is not yet in our sitemap.
Is the BOSCH CO21 Cobalt M42 21-Piece Set worth it?
Based on 1 Reddit owner comment, the BOSCH CO21 Cobalt M42 21-Piece Set scores 3.6 out of 5 (owner comments average 4.0 stars), and the theme owners raise most is metal drilling (1 mention).
Who it suits
- You care about metal drilling (1 positive owner mention)
Who should skip it
- Not observed: no recurring complaint theme yet.
What Reddit owners say
1 positive and 0 critical owner comments. Quotes link to the original Reddit comment.
Key specs
As listed on the Amazon product page we checked; missing fields are never estimated.
- TOUGH: The Bosch CO21 Drill Bit Set is manufactured from cobalt for drilling in hard and abrasive materials such as stainless, cast iron, and high-density metal. Also useful for general drilling in light-gauge metal, wood, and plastic.
- ACCURACY: Featuring a no-skate split-point tip for clean, precise holes and accurate starts.
- RELIABLE: The three-flat shank design promotes better grip and guards against slipping on bits 3/16 in. and larger
- PERFORMANCE: Designed for very high drilling temperatures for superior performance in stainless steel. Bosch Cobalt Metal Drill Bits are solid, reliable, and provide 4X longer life than standard high-speed drill bits.
- VERSATILITY: Includes laser-etched marking to provide clearly marked bit diameter. Included bit sizes: 1/16 in., 5/64 in., 3/32 in., 7/64 in., 1/8 in., 9/64 in., 5/32 in.,11/64 in., 3/16 in., 13/64 in., 7/32 in., 15/64 in., 1/4 in., 5/16 in., 3/8 in., 1/2 in.
| Brand Name | Bosch |
|---|---|
| Model | CO21 |
| UPC | 000346471540 |
| Set Name | 21-Piece Assorted Set |
| Unit Count | 1 Count |
| Global Trade Identification Number | 00000346471540 |
| Part Number | CO21 |
| Number of Pieces | 21 |
| Item Type Name | CO21 Cobalt Metal Drill Bit Set (21 Piece) |
| Item Weight | 1.1 pounds |
| Cutting Diameter | 0.5 inches |
| Item Dimensions | 4.6 x 9 x 1.5 inches |
| Material Type | Stainless Steel |
| Finish Types | Titanium |
| Shank Type | 3-Flat |
| Surface Recommendation | Cast Iron,Metal,Plastic,Stainless,Stainless Steel,Steel,Wood |
| Cutting Angle String | 135 degrees |
| Tool Flute Type | Spiral |
| Point Style | Split Point |
| Number of Flutes | 2 |
Drills Supply is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Commissions never affect scores, rankings, or verdicts.
FAQ
Is the BOSCH CO21 Cobalt M42 21-Piece Set worth it?
Based on 1 Reddit owner comment, the BOSCH CO21 Cobalt M42 21-Piece Set scores 3.6 out of 5 (owner comments average 4.0 stars), and the theme owners raise most is metal drilling (1 mention).
What do Reddit owners complain about with the BOSCH CO21 Cobalt M42 21-Piece Set?
We have not observed a recurring complaint theme in owner comments yet.
How much does the BOSCH CO21 Cobalt M42 21-Piece Set cost?
It was $101.90 on Amazon when we checked on 2026-11-07. Prices change, so check Amazon for the current price.
Alternatives
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Read review →Drill America 29 Piece m42 Cobalt Drill Bit Set
3.3 (1 owner comments)
$166.06 (price as of 2026-11-07)
“My preferred ones Metal: Drill America or Norseman.”
Read review →3.6 (10 owner comments)
$349.99 (price as of 2026-11-07)
“For example, Norseman 22903 1/16 in.”
Read review →Keep deciding
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Last updated 2026-11-07. Amazon listing ASIN B06XY7W87H.