highly-frequency weldings: highly-frequency weldings refuses to manual weldings long service life Strong and highly efficiency adsorption: highly strength adsorption screws to slippage, more to work highly hardnessed and durability: highly-frequency quenching, hardnessed up to HRC55, not easy to be deformed Electroplating technology: polishing to maintain original hardnessed is not easy rusted resistance Hardened steel forging rod head: highly heat steel forging highly hardnessed, good toughness, highly torqued, Manufacturer: SHANGYAKEJI