caster wheel material:pu caster wheel diameter:100-200mm caster wheel width:45mm caster wheel surface:Zn frame:rigid type,swivel type,swivel with brake ... type,it is more stable,flexible.surface: the caster wheel's surface is Painted by Zn,resist oi,rust,corrosion ... ,protect the ground, can used in vulcanized ground in factories. heavy duty PU round caster wheel