Karebac LR5C150 Grit Premium Gold 5-Inch PSA 150 Grit Discs Stearated C-Weight Aluminum Oxide , 100-Pack Used for wood metal plastic fiberglass paint primer solid surface materials composites Open coat grain with a non-loading stearate minimizes loading with a cool cut for longer lasting abrasives Strong C-weight paper backing P graded aluminum oxide grain provides fast smooth cut while fracturing to create new cutting services extending abrasive life Full resin on resin bond adheres the grain to the cutting surface making the disc waterproof