Stainless steel casters are divided into 4 series, which are Mini Duty S26(35-50kg), Light Duty S34(70-90kg), Medium Duty S54(130-150kg) and Heavy Duty S71(380-450kg). The frame with the screw and lock nut are made of 304# stainless steel while the ball bearings are made of SUS 440C stainless steel. 1.5", 2", 2.5", 3", 4", 5", 6" and 8" PA or PU wheels can be matched to different sizes of the frames. Stainless steel casters have the better feature in corrosion resistance than plain steel ones. They are clean and easy to maintain, which makes them popular in Food Industry, Medical Industry and the factories in the areas by the sea.