Genuine diamond grit, impregnated onto hardened steel files The six shapes included are hand, crossing, barrette, round edge joint, slitting and piping. Packaged in a vinyl storage pouch. Made in the U.S.A. Can be used on all hardened materials, glass, carbide, hardened steel. These Diamond Files are made in the USA, and have genuine Diamond particles impregnated into hardened steel. This set is a must for hobbyists and technicians. these files can be used on carbide, glass, ceramics and hardened tool steel.