Where is the high-efficiency filter with stable quality and how to choose it?

There are still many manufacturers of high-efficiency filters, mainly distributed in Zhejiang and Guangdong, depending on your situation. At present, foreign brands include AAF and Conocophillips, and there are first-line brands such as Meiai, Huatai and Su Jing in China. I remember a company called Kunshan Jiahe Purification. If it is in the southwest, you can go to their branch, Chongqing Xinjiahe Purification. The filter there is still relatively stable.