Robert Bosch Tool Group BL21A Black Oxide Drill Bit Set 21pc

Product Description

The ROBERT BOSCH TOOL GROUP BL21A is a 21-piece black oxide drill bit set designed for general-purpose metal and material drilling applications. Each bit carries a black oxide coating that reduces friction during drilling, extending bit life in everyday use. The set includes a no-skate tip geometry for clean, accurate starts without center-punching, and bits sized 3/16 inches and larger feature a three-flat shank for improved chuck grip and reduced slippage. Size markings are high-visibility and clearly stamped on each bit for fast identification on the job. This set is suited for professional tradespeople and general contractors who need a reliable multi-size bit assortment on hand.

The BL21A covers a wide range of common hole sizes from 1/16 inch up to 1/2 inch, making it practical for residential and light commercial work across HVAC, plumbing rough-in, electrical, and general carpentry tasks. The set includes 21 bits: two 1/16 inch, two 5/64 inch, one 3/32 inch, one 7/64 inch, two 1/8 inch, one 9/64 inch, one 5/32 inch, one 11/64 inch, two 3/16 inch, one 13/64 inch, one 7/32 inch, one 15/64 inch, two 1/4 inch, one 5/16 inch, one 3/8 inch, and one 1/2 inch bit. The assortment addresses the most frequently called-for drill sizes in trade work without requiring a specialty set.

Key Features

• Black oxide coating reduces friction and heat buildup during drilling
• No-skate tip design enables clean, accurate starts on metal and other materials
• Three-flat shank on bits 3/16 inches and larger prevents bit rotation in the chuck
• High-visibility diameter markings allow quick size identification
• 21-piece assortment spans 1/16 inch through 1/2 inch for broad coverage
• General-purpose construction suitable for metal, wood, and plastic substrates

Compatibility

Designed as a general-purpose drill bit set compatible with standard 3-jaw keyed and keyless chucks on corded and cordless drills commonly used in trade applications.

Installation Notes

These bits are installed and removed by a licensed or journeyman-level tradesperson using a standard drill with a compatible chuck. Ensure the drill is powered off and unplugged or the battery removed before changing bits. Seat the three-flat shank fully into the chuck and tighten securely before drilling to prevent slippage. Use appropriate cutting fluid when drilling ferrous metals to extend bit life.