6" x 2" Rubber on Ergolastomer Wheel Heavy Duty Spring Gate Caster6" x 2" Rubber on Ergolastomer Wheel Heavy Duty Spring Gate Caster Rust free and suitable for wash down, high humidity, and any outdoor environments. The glass nylon core is designed to increase load and impact capacities while the cast polyurethane tread offers shock absorbing cushioned ride allowing it to roll over debris easily and quietly without damaging floor surfaces. Tread: Solid Cast Polyurethane Core: Glass filled Nylon Bearing: Sealed