The Trick Tools Ron Covell Round-Over Dies, used for rounding edges on fenders, are precision machined from heat-treated steel and can handle up to 16-gauge mild steel. Rolls, which can be purchased as a set or individually, are available in 5/16", 1/2", 1" and 1-1/2". The dies were originally designed for the Pexto 622 rotary machine, but adapter sleeves are available to fit other brands of bead rollers and rotary machines.