PPR pipes are smooth to outside and inside, standard caliber, no distortion.The sizes are from 1/2" to 4" . Dear Sir or Madam:We are a professional manufacture ( Taizhou Zhuoxin Plastics CO.,Ltd.) that produce plastic fittings (PPR / PVC fittings), plastics ball valves, plastic taps and, PPR pipes mould, ect.If you can give us a chance to cooperate with you, we are always in a position to quote ...