Medium heavy duty caster,size from 4" to 6". Wheel material ... 4mm Fork thickness is 3mm Rolling castor wheel, light duty casters, Medium duty casters, medium heavy duty caster, Heavy duty casters, PU caster,PP Caster,PVC Caster,Rubber caster, ... China. Eletroconductive caster,elastic rubber wheel.Anti static caster. Transparent Casters, Skate castors, wheels, furniture caster, Racking caster wheel, ...