Replacement Caster - 3 x 1 1/4 . * HD Casters Have Threaded Stem For Extra Security And Safety. * All Single Wheel Castes Come With Removable Bolt And Locknut Allowing Disassemlby For Easy Cleaning And Removal Of Build-Up Grime Thread Or Anything Else That Your Wheel Picks Up During Normal Usage. * This Caster System Will Add Longevity To Your Casters. * Swivel: Double Ball Bearing With Hardened Raceways For Extra Strength. * Cover: Helps Protect Swivel Bearings. * Construction: Heavy Guage Cold Rolled Steel Formed For Strength.