Twist FX Surface Cleaning Discs wont damage surfaces or leave residue. Excellent for working in confined spaces, the non-woven construction quickly removes oxide, scale and gaskets, and offers a long life. The Twist quick-change system makes changing discs quick and easy, reducing downtime. Simply twist to the backing pad and start working. Use with 2 backing pads (sold separately): WAL04X202 medium (orange), or WAL04X203 hard (black). For use with all metals. Package of 10.