Material: Fork: steel plate, zinc-plated.Tread: thermoplastic rubber TPE, grey.Wheel body: plastic, screwed.Wheel mounting: ball bearing.Swivel bearing: double ball wreath.For indoor use. Low-noise operation with low rolling and swivelling resistance. Non-marking. The tread is slightly oily and can cause contact discolouration on sensitive surfaces.Temperature range: -20°C to +60°C.