Bulk Packaged 6.4 x 11.1 mm - 1/4 x 7/16 inch - Bullet Diamond Coated Burr, 1/8 inch shank. For use with Dremel Rotary Tools. Diamond coated accessories will cut into glass, wood, metal, stone, practically anything. For longer life, use with a cooling agent such as Eurotool Cut Lube.