Material: Metal material which is a heavy material in construction for long service life. Universal: There are one hex socket and three square adapters in different sizes, and you can use the right one for different needs. The universal SDS plus shank fits most screwdrivers, drills and electric chucks. Convenient: The small size allows you to take your bit extension anywhere to do every job and fits in many tool bags. Plus - 65mm x 1/4" square, SDS Plus - 65mm x 3/8" square, SDS Plus - 75mm x 1/2" square head. Package Contents: 1 x Hex Extension Adapter. 3 x Square Extension Adapters.