This 8” x 3” Polyurethane on Cast Iron wheel is a polyurethane tread chemically bonded to cast iron core. Polyurethane on cast iron wheels offer higher weight capacities while administering good floor protection and gentle, quiet rolling operation. Polyurethane wheels are non-marking, non-staining, and non-conductive. Also, immune to oil, grease, water, and most solvents. This wheel works exceptionally well in both indoor and outdoor environments; however, the cast iron core can rust. Temperature range: -40° F to 180° F.