When you want use diamond coated grinding disc with magentic backing please select metal master lap otherwise used the plastic and aluminum backing plate with pressure sensitive adhesive and vlecro.Diamond Plated Disc and Flat Laps is the perfect tool for the commercial cutter or serious hobbyist. Diamond top plates just 1.0mm thickness is easy to apply to backing plates. All backing of diamond top plates laps can be pressure sensitive adhesive , magnetic and none backing. Diamond discs and lap are available in a wide range of mesh sizes for rough grinding and fine grinding of all precious gem material applications include performing rough and fine grinding on faceting material plus general lapidary grinding when precision is required. A controlled concentration of diamond bonded onto a precision backing plate ensures consistent grinding and surface finishes. Diamond discs can put on a precision ground backer such as master lap in plastic,metal and aluminum materials.