1. Use: diamond grinding wheel for precision machining of glass: glass thickness, jade, jade, , and other building materials. 2. the correct use method: electric drill speed 3600 rpm, bench drill and machine speed in 6000 ~ 10000. The water must be polished so as to achieve the best effect. 3. About how to choose the explanation: if the material thickness of 8mm, choose the appropriate 8mm diamond grinding wheel. Specification: Shaft diameter: 6mm Outer diameter: 20mm Grit:150 Width: 4mm Colour: As Shown Material: electroplating emery Package Contents: 4 x Diamond grinding wheel Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.