These spline bits are crafted and made of superior S2 Steel (carbon, silicon, manganese, chromium, molybdenum and vanadium) for designated maximum torque requirements. Drop forged and carefully heat-treated, they are perfectly constructed for overall bit body strength but still gentle on screw heads Schrauben Schonenderes minimizes stripping and wearing damages. The PE-HD Blow Mold Case is for easy storage while providing excellent protection for your bit sockets and giving you high work portability.