Made of high quality silicon carbide and water proof sand paper. The abrasive papers can be used for wet and dry sanding. Electro coated ensures the grit distributed uniformly. Prevent clogging, anti-static, good flexibility, wear resisting, that provides outstanding life and superior finishes. It's more effective used wet because clogging is reduced by particles washing away from the grinding surface. It can be used for mold surface precise sanding, and also in stone, lacquer surface, mirror surface treatment such as headlamps polishing. Waterproof sanding discs can be used for dry sanding too, it's more hard than white dry sandpaper. Disc grips to the appropriate back up pad attached to an orbital or DA disc sander or angle grinder. 
Wood Furniture finishing, drywall sanding, automotive metal polishing, almost all the polish work can be finished with them. Just choosing the right sandpaper grit for your project.
Grit refers to the average particle diameter. The smaller the grit number is, the coarser it is. The larger the grit number is, the finer it is.