The Walter Surface Technologies Enduro-Flex ALU Flap Disc was developed for working with heat-sensitive metals such as aluminum and other non-ferrous alloys. These flap discs are formulated to maximize performance and drive productivity, the company says. They are iron-free, sulfur-free and chlorine free, with zirconia aluminia grain blend to optimize blending and finishing performance on any aluminum surface for a consistent finish without discoloration. Enduro-Flex ALU discs are available in 4-1/2”, 5”, 6” and 7” diameter sizes with grit values of 40, 60 and 80.