6" x 2" Polyflexon Cast Wheel Swivel Caster - 900 lbs. Capacity6" x 2" Polyflexon Cast Wheel Swivel Caster The unique flex compound used for the Polyflexon wheels offer a semi cushioned ride, ideal for workshop or warehouse applications where small debris or thresholds are present. The rounded tread and sealed precision bearings provide low friction swivel and roll. Tread: Flex Compound Polyurethane Elastomer, Non Marking, Chemically & mechanically bonded to Core Core: Cast Iron Bearing: Roller Bearing Rig: Zinc