Precision ground 82° tip for countersinking most machinable metals, wood or plastic Made from industrial grade high speed steel for increased durability Includes a black oxide finish for added corrosion resistance Five flute design reduces vibration for smoother drilling and extended life 1/4" round shank fits all handheld and stationary drills Includes: 1/4", 3/8", 1/2", 5/8", and 3/4" .