3 Sizes Hex Drive Power Drill Bit Set Socket Extension Adaptor 1/4'' 3/8'' 1/2'' Stainless Steel Locking Ball Ensures Secure Fit. Sockets Snap-On Tightly & Won't Slip Off. 1/4-inch Hex Shank Prevents Stripping During High Speed Drill Operation. Super Strong Heat Treated Chrome Vanadium Steel for Normal & Impact. Converts All Power Drills into Speedy Socket Drivers. Applies to the screwdriver handle or electric screwdriver tools (hexagonal hole or three jaw chuck can be) driven sleeve is used, can be the original hexagonal side after installation on size into square size, which can be used for the installation of the sleeve, is a good accessories to convert.