They can be used on acrylic and all metals. Sold individually and available in various sizes: A-1/2 Coarse, B-1/2 Coarse, C-1/2 Coarse, D-1/2 Coarse, E-1/2 Coarse, A-3/8 Coarse, B-3/8 Coarse, E-3/8 Coarse, 88A Coarse, 82T Coarse, 73C Coarse, 52D Coarse, 52C Coarse, 51A Coarse.
