Amazon カスタマー 1 I use Amazon for almost 20 years and it is the first time I write a product review to express how disappointed I am with the Panaracer inner tubes.Very poor quality of manufacturing, this is unacceptable at this price point.I wonder if it is a fake product at this point.- Valve thread is badly finished and the little metal bur does cut finger skin every time I try to open/close the valve.- Both tubes on the bike are flat after 4 months of purchase. The bike was stored at the home during winter with only 50% of the air. Both tires are punctured and don't retain air as tubes are porous.I will never buy again Panaracer tubes