Material: Steel High carbon steel, high quality material to avoid during use. General Use: These extenders, adapters and reducers are designed for Impact use and feature balls spring-loaded detent to lock sockets securely, while through-holes at the drive end of adapters and reducers lock onto the drive shaft. convenience no matter which tool you choose to use. Ideal for DIY, household maintenance and most general repairs High Quality: The extension adapters are made of chrome vanadium steel heat treated with a black oxide coating. Adapters and reducers are premium high strength chrome plated steel with a manganese phosphate coating to help resist rust and corrosion. a lifetime of use. Widely Application: Suitable for 1/4" quick change chuck systems or directly into the drill chuck. Any cordless electric drill in a nut driver. Convenient for quick driving of nuts, bolts and fasteners etc. Spring-loaded ball bearing on head holds sockets securely. Material: Chrome Vanadium Steel (CR-V) Size: 1/ 4*1/4*65mm Length ------ 1/4" shank can be converted to 6.35mm square head 3/8*1/4*65mm Length -- ----The 1/4" shank can be converted to 9.4mm square head 1/2*1/4*72mm Length ------ The 1/ 4" can be converted to 12.6mm square head