3M DRYWALL Sanding Sponge 4PK, Dual Grit Block, 2 7/8" x 4 7/8" x 1"

This sponge features conventional 3M abrasives and is made with durable, flexible foam. The block shape makes it easy to hold and sands flat, contoured, or irregular surfaces. Sanding is an integral step in preparing a surface to receive a coating.

eBay