Feature: Aggressive and durable made with quality diamond powder impregnated in resin. The pad holder are with water feed hole, can be used for wet polishing. Diamond polishing pads 4 inch wet 19 piece set granite stone concrete marble. Strong grinding force and smoothness. High wear resistance, polishing effect is good. Perfect for granite, concrete, marble, stone, tiles etc. Specification: Diameter: approx.4” (100mm) Backer diameter: approx.4”(100mm) Pad thread: M14 female thread Pad grit: 30, 50, 150, 300, 500, 800, 1500, 3000 Recommended RPM use is 5000 RPM or less Package included: 3pcs x 30 grit diamond polishing pad 3pcs x 50 grit diamond polishing pad 3pcs x 150 grit diamond polishing pad 3pcs x 300 grit diamond polishing pad 2pcs x 500 grit diamond pol.