1. Check whether the trademark of the reverse osmosis membrane is a red diamond with the word DOW in white (TW series household membrane elements).

2. The appearance of Dow reverse osmosis membrane module is rough, and the fiberglass shell is uneven. Membrane modules are generally dry films before leaving the factory. The new ones are brighter in color and have clear labels.

3. Each membrane module has a serial number; you can check product information from the Product Division of DOW Chemical Company or the first-level dealer (Beijing Antai Jiusheng or Shanghai Hanhua) accordingly.