【material】Steel Carbon steel, high quality material, should not be used when using. 【General Use】 These extensions, adapters and reducers are designed for impact use and feature spring-loaded stop balls to securely lock the sockets, while clearance holes on the drive end of the adapters and reducers lock onto the drive rod. Convenience no matter what tool you're using. Ideal for DIY, home maintenance and most general repairs 【High quality】Extension adapters are made from heat-treated chrome vanadium steel with a black oxide coating. Adapters and reducers are made from high-quality, high-strength chrome steel with a manganese phosphate coating to resist rust and corrosion. a lifetime of use. 【Wide application】 Fits 1/4" quick-change chuck systems or directly into drill chucks. Any cordless drill with a socket wrench. Practical for quickly screwing in nuts, bolts and fasteners, etc. Spring-loaded ball bearing on the head holds sockets securely.