Material: Chromium vanadium steel, industrial/automotive/mechanical use, electric manual maintenance tool. Includes: 8 pieces -4 x 1/4 ", 2 x 3/8", and 2 x 1/2 "drivers, each with a 1/4 inch hex shaft handle. Quick set square head bolts and hex head screws.Safe and durable: Chromium vanadium steel material is suitable for heavy impact conductors. Suitable for screwdriver handle tool drive sleeves or quick change 1/4 "chuck systems or direct entry into drill chucks, changing your hand drill bit set to a driven drill bit set. The 1/4" hexagonal handle is suitable for all quick change chucks and standard drill bit chucks.Purpose: This adapter kit is designed to provide secure locking extensions for existing tools. Provide additional length to enter a large amount of difficult to reach space. The spring ball lock ensures a tight fit to the driver's head, preventing slipping during use. After specialized processing, it can be firmly installed in handheld drivers, drilling drivers, or impact wrenches. The spring loaded ball bearing is firmly fixed on the square drive head bracket sleeve.Multi functional: Used for installing hexagonal tools such as pneumatic screwdrivers, electric screwdrivers, pneumatic drill bits, manual screwdrivers, etc. Transforming the electric drill into a high-speed nut driver set, these adapter tools can be used to connect socket sets/drilling sockets/drill bit sockets/hexagonal sockets/socket wrench sets/ratchet universal sockets/impact socket sets/standard sockets/SAE metric socket sets/deep socket sets/5, 6, 7, 8, 10, 12 point millimeter socket sets/spark plug sockets to the electric drill.General purpose: This 8-piece set of hexagonal shank drill bit driver extension rod set is designed to meet various needs. Tightly and firmly installed in the drill chuck or handheld screwdriver. This includes the most common drill bit sizes of 1/4 ", 3/8", and 1/2 "variable shank sizes. Regardless of which tool you choose to use, it provides versatility and convenience. It is very suitable for DIY, home maintenance, and most general repairs, and is not suitable for industrial work. It is an excellent tool supplement for any toolbox set.