These 1-1/2 inch diameter cut-off wheels are the same type used by the steel industry, but in miniature sizes for miniature work. The fiberglass reinforcement resists breakage common to plain cut-off wheels. For non-ferrous materials including glass, ceramic plastic, aluminum, copper, brass. .050 inch thick, Choices include 1/16" screw head( standard), 1/8" or 1/4" screw head. Use on all rotary tools.