Hard rubber back-up pad. Pad assemblies come complete with a 2″ (5.1 cm) steel shaft and adapter. Provides firm support for Scotch-Brite™ Roloc™ Surface Conditioning Discs and 3M™ Roloc™ Bristle Discs. The 3M™ Roloc™ Disc Pad Assembly, is designed to support 3M™ Roloc™ 2 or 3 Inch Diameter Abrasive Discs, and can be mounted directly to tools with 1/4-20 EXT threaded shafts.