Bulk Packaged 7.1 x 11.1 mm, 9/32 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.