Irwin 4935655 12" Lock-n-Load Quick Change Bit Holder Extension for 7/16" Hex Shank For 7/16" Hex Shank Bits 12" Overall Length Carbon steel construction sleeve and body for durability and life Lock-n-Load system for one-handed quick release Patented jaw design holds bits securely on 6-flatted shanks, as well as ball detent bits