For 1/4" 5/16" 3/8" Dr Nut Drive Bits for Power Driver Tool for Socket Set Hex Screw Set includes 1/4", 5/16" and 3/8" Size sockets Each socket is roughly 1-1/2" in length with a lock on neck Material : Carbon Steel Hexagonal Head magnetic holder Use: for Putting in Tek Style Self drilling Screws and Fixing Hex Heads