Cushion grey PU tread is non-marking material. This caster will leave any mark on your clean & shiny floor. The PU wheel is also resist to water, oil, grease and some light chemical.
Shiny Nickel coating enhances rust and corrosion resistant. Steel hubs are soldered with the cast-iron core so it is hard for dust, water and silk to intrude the ball bearing and shaft. Thus lessen the needs for maintainance.