This set of Center Positioning Dies includes 11 nylon dies, from 1/8" to 1" diameter. To create a washer shape, you punch a hole in your sheet metal to the size of the inside diameter of the washer you wish to create. The disc so created is set aside and your sheet metal is moved to the hole in your disc cutter corresponding to the outside diameter of the washer you are making. Then you insert a positioning die, in the same size as the outside diameter of the washer you are making, tapered end first, to center the hole in your sheet metal. Remove the positioning die, replace it with the same size punch, strike the punch, and the result is a washer with a concentric hole.