3M 7010308594 Back-up Pad is a medium density, quick change attachment type product. It is black in color and suitable for various applications such as deburring, finishing, grinding, polishing, and surface preparation. Compatible with disc sanders and right angle grinders using a 1/4-20 INT thread size. Ideal for industries like metalworking, builders hardware, medical instruments, metal fabrication, plating & polishing, plumbing fixtures, and turbine engines. Inside diameter is 0.0 NP in metric.