Unique Design: the anti-dropping steel ball is better fixed: the self-locking device is not easy to slip or fall off and cause situations. double R design, greater bearing capacity of Application: It can be used for installation on tools with shapes such as pneumatic screwdrivers, electric screwdrivers, air drills, electric drills, and manual screwdrivers Various Specifications: 1/4" 3/8" 1/2" Extension Drill Bits Bit Set Power Tools Usage: suitable for screwdriver handle or electric screwdriver tool ( three-jaw chuck) to drive the sleeve. After installation, the joint can be converted into a square for head, which can be used for the installation of the sleeve. A powerful tool for conversion Convertible Head: 1/4 handle can be converted to 6.35mm square for head, 3/8 handle can be converted to 9.5mm square for head, 1/2 handle can be converted to 12.7mm square for head, Manufacturer: BOYANDM