HHIP 8 piece new expanding Arbor set includes the arbors with alloy wrenches in a handy wooden stand. To use, chuck arbor to be used in the machine then tighten the expanding screw so that arbor expands .005". Machine the arbor to the length and size required then loosen expanding screw. Position the part in the arbor and tighten the expanding screw. Includes sizes 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1 and 1-1/4" arbors. Arbors through 5/8" are 3" long and arbors through 1-1/4" are 4" long.