Coarse diamond grinding burr sets Shank Material : Alloy ,Shank Diameter : 6mm/ apro 1/4 inchHead Diameter : 8mmTotal length: 2-3/8" (60mm)Grit : 60 (coarse) or 120 ( fine ) , please select the grit what you needed.60 grit grinding bit heads shape include: Umbrella type shape , Sphere shape, cylinder shape, bullet shape, taper shape ,Inverted trapezoid shape120 grit grinding bit heads shape include: Umbrella type shape , Sphere shape, cylinder shape, bullet shape, taper shape ,Inverted trapezoid shape Can applied to hard material below: sandstone and marble, granite, basalt, limestone, dolomitefloor tiles, glaze, underglaze, blue and white, pink ancient, wall tilesIron, aluminum, stainless steelprecious stone, metalsceramics, fiberglass and plasticused the burr on bathroom countertop Work well with simple stone carving Great for stone / glass carving Please select the grit you want before ordering