These grinding discs uses diamond as abrasion and combined with composite material. There is sticky cloth on the back which can stick on milling machine. They are mainly used for process, repair and renovation on stones, glasses, floor tile, marble, concrete, cement, etc. With strong grinding force, good flexibility, durability, they are ideal stone grinding tools and stones will have a good glossiness and smoothness after polishing. Features: 1, Use diamond as abrasion and combined with composite material. 2, Sharp, wear-resistant and high efficiency, strong grinding force. 3, Polish quickly, durable and long service life. 4, No color left on stone after polishing, good smoothness. 5, Mainly used for stone, glass, ceramics, crystal, ceramic stone, concrete, etc. Specifications: Materiel: Diamond + resin Diameter: 100mm / 3.93" Thickness: 4mm / 0.15" Granularity: 50#+100#+300#+500#+800#+1500#+3000# Weight: 225g(approx.) Package Includes: 1 Set(7pcs) x Grinding Discs Note: 1, Please add water when you operate. 2, Please allow 1-3mm error due to manual measurement. Thanks for your understanding. 3, Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.