Muvtons premium soft durometer polyurethane threaded wheels 83° ±3° shore a, firmly bonded to precision machined cast iron cores. These wheels have been designed in response to noise problems and allow loads to be cushioned. The use of 'lively' polyurethane materials allows these wheels to 'flex & roll' over debris and obstacles without picking up objects. They are non-marking and floor protective. Tested & guaranteed against bond failures. Wheel bearing options : sealed precision ball bearings, tapered roller bearings or roller bearings. Temperature range: -20° c to +85° c. Tread options : anti-static ; conductive wheels are.