Heat treated, durability, has high hardness, not easy to wear Please make sure you choose the right drill bit and control the right speed of the drill This greatly prolongs the service life of the drill bit steel, hardness can reach HRC60 degree The allen screwdriver is, which helps to keep and bolts stuck to Can improve your work efficiency Perfect for industrial maintenance in manufacturing, electronics, and automotive industry, as well as household repairs and projects, Manufacturer: LiRRvb