IVY Classic 10777 5-1/2-Inch Self-Feed Bit Extension, 7/16-Inch Hex Power Shank, 1/Tube Extends any 7/16-inch hex shank self-feed bit an additional 5-1/2-inches, Swift Bore (Registered Trademark) High-carbon steel construction, precision ground and polished with 7/16-inch hex shank for secure grip Two set screws and a hex key included. To fasten the shank in place, use the hex key to tighten these screws Compatible with all 7/16-inch hex shank self-feed bits (IVY Classic self-feed bits: 10761, 10763, 10764, 10765, 10766, 10768, 10769) Length: 5-1/2-inch, Shank: 7/16-inch