screwdriver bits for drill，Imported S2 material is adopted. S2 steel is stable and wear-resisting, shock resistant, stron

double square screwdriver bits,The batch head made of high quality S2 steel, combined with special heat treatment techno

Ph1 Ph2 Ph3 Screwdriver Bits,Imported s-2 tool steel is used.S2 tool steels are alloys of carbon (C), silicon (Si), mang

wide slotted screwdriver bit,The batch head made of S2 alloy steel has a hardness of about 60HRC.After special heat trea