Have a North Brothers, or Stanley Yankee Spiral Ratchet Screwdriver? Need a Philips head bit for it? This adapter is for standard 1/4" Hex drive bits, giving you the ability to buy any type head (hex tip) or length head you wish (hex bits are found at any hardware store). This adaptor is made in the USA and comes in three sizes on the Yankee connecting end, this one is .312 (5/16") diameter for the No. 31A and 131A and some other models as well. I also have one smaller size shank type available at this site. On the hex end there is a coil spring the grasps the hex bit when it is inserted keeping it from falling out. (Don't use bits that are stepped down as they will become stuck in the adapter. Small notches are fine, like the ones shown in the pictures. You also get one hex drive Philips bit with each adapter (the slot head bit is not included). A real nice addition to your bits for a Yankee screwdriver! Made in U.S.A..