These Step Rolls from Mittler Bros. suit all Mittler Bros. Bead Rollers as well as all bead rollers with standard 3/4in shaft and 1-18in throat height and are CNC Machined from either Heat Treated Steel or Nylatron for use on softer materials such as Aluminum, Brass and Copper. Throat Height - 1-1/8" Outside diameter - 2-1/2" Inside (sha