Bulk Packaged 3 x 7 mm, 1/8 x 9/32 inch 400 Grit Round End 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.