They are resistant to water, oil, and grease and will keep you safely moving forward.
Listing is for one (1) Service Caster Series #20 rigid caster with a 6" diameter by 1-1/4" wide thermoplastic rubber wheel capable of supporting 300lbs. Mounting options include top plate, bolt hole and standard and metric threaded stem sizes. 6 Inch Thermoplastic Rubber Wheel Rigid Top Plate Caster The zinc plated finish provides durability under any condition, and the soft, quiet and non-marking thermoplastic rubber wheels perform especially well on hard surfaces such as concrete, tile, and wood.