Bulk Packaged 2 x 6.3 mm, 5/64 x 1/4 inch 400 Grit Cylinder 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.