I dont really know that there are PU bumper.. dont shoot me, really dont know.. all the time working for company that supply to Proton and P2.. only know that OEM bumpers are made of PP.. these things (PP) can come in what ever color they want as the color is blended into the material.. but normally its grey.. But if there is really PU bumpers, then it should b very flexible.. even more flexible than the PP.. but one thing for sure if PU then the material will look a bit like rubber as the material is ussually substitute/replacement to rubber.. abit shinny and clear as in the super pro high performance bushes..