Aluminium oxide grain,C-wt backing. For wood,metal and auto Sanding Disc / SD-A207 / For Plaster Features: Aluminum oxide grain; red color; C-wt paper backing; better used for wood and dry wall.Benefits: Fast, aggressive cutting action, consistent finish; Superior strength and tear resistance, flexible; Eliminates delamination to back-up pad. We have produced various sizes on customers' request. ...