Generally, there is no such ranking, but bare pipes generally refer to PVC pipes, mainly Jinde brands. The quality is not only expensive, but also the quality of essential oils can be moderately priced. The quality of Japanese products is good, but there are many fakes. The quality of Aikang can be mainly in East China, and the quality of fashion is also good. The quality of Wei Xing in the middle price is still ok, and the quality of these brands in the middle and high price is similar.