The self-feed bits in DeWalt's DW1649 eight-piece kit make use of aggressive, replaceable spurs and a unique two-cutter design to cut rough holes in wood quickly and efficiently. The geometry of these bits is engineered to provide extended bit life, and an open-tooth design allows extra resharpenings to save you money. Also offering a 7/16 In. ball groove shank that has flat sides to prevent the bit from slipping in your drill's chuck and allows you to switch from one application to the next quickly, this kit includes a 5-1/2 In. extension piece, 1-, 1-1/8-, 1-1/4-, 1-1/2-, 1-3/4, 2-1/8-, and 2-9/16 In. self-feed bits, and a convenient set of replacement parts in a durable kit box that makes it easy for you to keep your tool kit organized on the go.