For use with 1″ diameter posts. Resilient or polyurethane tread. Casters with zinc, stainless steel, and polymer boot available. For electronic handling, conductive casters and vibration dampening casters available. Donut bumper included with all stem casters. Swivel casters have a temperature rating of -15°F (-26°C). Note: These stem casters cannot be used with Master Trak Shelving.