This Ryobi Roundover Router bit set comes with 4 pieces so you are ready to take on different jobs. The sizes include 3/4, 1, 1-1/4, 1-1/2 inch. Heights differ. Please see images. These bits are designed to be ready to take on wood and create roundover designs. The edges are carbide as well, elongating the life of these bits. The shank is 1 / 4 inch and will be accepted by most routers. An allen key is included to make adjustments as needed.