... Material:Nylon,PU, Rubber, Super artificial rubber. Size:v2' -5inche Caster is important compoent of Wei Tao-line flow pipe system ... ,which commonly used in worktables, carts,racks.There is caster iron rubber wheel ,super artificial rubber wheel ,PPwheel,phenolicaldehyde wheel ... 's divide two style:With brake &Without brake PU switch caster for pipe rack(Shelf)