1、This bit extension holder is made of carbon steel and chromium-vanadium steel for durability 2、It is designed for 1/4inch hex shank bits, good concentricity 3、The holder has extra-strength magnetism so it can hold bit securely 4、Suitable for pneumatic screw drivers, electric drills, electric screwdrivers, screwdrivers 5、Widely used for automotive repairing, hardware maintenance, hobby, home, etc Features: This bit extension holder is made of carbon steel and chromium-vanadium steel for durability. It is designed for 1/4inch hex shank bits, good concentricity. The holder has extra-strength magnetism so it can hold bit securely. Suitable for pneumatic screw drivers, electric drills, electric screwdrivers, screwdrivers. Widely used for automotive repairing, hardware maintenance, hobby, home, etc. Specifications: Materiel: Carbon steel+Chromium-vanadium steel Length: About 60mm (2.4in) Hex Shank/Socket Size: 6.35mm (1/4in) Quantity: 1 Weight: 22g(approx.) Package Includes: 1 x Bit Holder Note:Please allow small size error due to manual measurement. Thanks for your understanding.