Our Lathe Wheels come in three grits: FINE: green, 120 grit Especially suited for grinding porcelain teeth Long wearing and will not chip porcelain MEDIUM: black, 46 to 60 grit Excellent for trimming denture base plate materials, stone models and acrylic This top grade wheel is rapid cutting and will not clog at low speeds COURSE: white, 36 to 46 grit Developed for trimming base plates, acrylic, and stone models Aluminum oxide grit facilitates rapid shaping with minimum pressure Will not clog Generates little heat All three grits come in 3" x 1/4" and 3" x 3/8". All wheels have 1/4" lead reinforced center hole