PU wheel is also called PU perfusion wheel. Strictly speaking, PU is also a kind of plastic, but additives are added in the production process, so the performance is more superior, and of course the production cost also increases. Features of PU perfusion wheels: Elasticity can play a certain shock absorption effect (even better than inflatable wheels), good grip, not easy to slip, more wear-resistant, and good comfort. http://www.blyshares.com/pu-wheel/