GP21103 Professional Glass Polishing System - Removes Hard water damage, lime scale, scuffs and surface marks from any type of glass. Polish away hard water deposits, limescale, scuffs, surface marks, tree sap. Can be used on any type of glass surface including toughened glass and any automotive glass. Backing Pads Thread Size : 5/8''-11 Designed to be used with rotary polishing machined with variable speed control ( recommended speed 1000-2200rpm's Comes with Surface Sealant Specialist Coating to protect glass surface and make it water repellent.