Steelex 5in Polyurethane Swivel Caster Threaded Mount with Double Lock. They are excellent for a wide variety of applications where quiet operation high wear factor and high corrosion resistance are a concern. These 3" swivel casters have a 2-1/2" x 2-1/2" Plate and 220 lbs. capacity. Package Contents: Steelex Polyurethane Swivel Caster Plate Mount Steelex D2618 5in Polyurethane Swivel Caster Threaded Mount with Double Lock