The 5-ply buff is a polishing wheel used in metalworking & woodworking to buff or polish surfaces to a smooth & shiny finish. It is made of several layers of cotton fabric or yarn that are tightly compressed as well as stitched together to form a durable, multi-layered wheel. The number of layers in the buff determines its thickness as well as density, with a 5-ply buff being thicker & denser than a 2 or 3-ply buff.