[Multi-function] for installing hexagonal tools such as pneumatic screwdriver, electric screwdriver, pneumatic drill, manual screwdriver, etc. It is a good conversion accessory. For universal joint kits, impact and gear joint kits, universal joint kits, JACK and gear joint kits, JACK extension kits, kits of anti-collision sleeves. color design different color ring, easy to choose suitable. set - 3 pcs: 1/4", 3/8", 1/2", 1/4" Hex Head per piece, suitable for any fast - change bit chuck system. Converting any BIT to a solid spring loaded ball bearing with power nut securely holds the socket in place. Ink liners are tight and won't slip. [use] - great tool for any toolbox. This set of three hex screwdriver extension bars is designed to meet a variety of needs. Slide completely into spindle or hand screwdriver. It consists of the 1/4", 3/8" and 1/3" bit sizes that you use most often. Variable dimensions. Whichever tool you choose to use, it is versatile and practical. [material] - high quality 6150 Cr - v. Cr - V steel structure and heat treatment, high hardness, good toughness; Sandblasted surfaces can increase fatigue resistance. Size: 1/4*1/4*65mm long - 1/4" convertible shank to 6 square head ,35mm Length 3 / 8 * 1 / 4 * 65mm - 1 / 4 "convertible shank to 9mm square head 1 / 2 * 1 / 4 * 72mm long - 1/4" convertible shank to 13mm square head