Offering uncompromised water quality when cost is your main consideration. The fibreglass wrapped WW-4040 and WW-4021 deliver new standards in quality and performance for economic RO membranes, making them a perfect choice for the competitively priced market. With rejection rates of 98.5% which outperforms many established pure water production membranes, while at the same time, beating entry level imported inferior alternatives on price and build quality. This membrane is for any business that requires a high rate of filtered water with a crystal clear finish.