40/50 grit diamond, best on marble, and glass. For router stone with wood router bit. Use wet or dry. Aluminum or other coolant is recommended for long bit life. Product Name: Diamond Profile Bit Material: Temple Cutting Radius: 8 mm / 5/16 inch Shank Diameter: 12.7 mm / 1/2 inch Bearing Diameter: 13 mm / 1 / 2 inch Cutting Depth: 12.7 mm / 1/2 inch Overall Diameter: 31 mm / 1 1/4 inch Overall Length: 58 mm / 2.3 inch Color: Gold Tone Weight: 86g/Pieces Package Contents: 3 x Temple Profile Router Bit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in a little different from the real thing. The measurement allowed error is +/- 1-3 cm.