This is a new Yankee type screwdriver adapter so you can use your 1/4" drive socket set with this adapter, and your Yankee spiral ratchet screwdriver to form a nice nut driver combination! The adapter will fit many different screwdrivers, made by Stanley, North Brothers, Greenlee, and some made in Germany models. These are some of the North Brothers or Stanley numbers this adapter will fit: No. 135, 133H, 233H, 35, and several others that have the smallest diameter shank size (7/32" or .218" diameter). The 1/4" square drive end has the normal spring loaded ball to help hold your sockets in place. The adapter work great on the sockets we tested including vintage Craftsman sockets! We should also mention the Yankee screwdrivers make excellent nut drivers as well! A very useful tool! If you are interested in the larger sizes, please email us, as we may be able to get the larger socket driver adapters as well. We do have hex head adapters for sale, for the larger size screwdrivers on this website.