Membrane Part # is WQCM11-50
Highest quality original factory replacement membrane for the 11" 50 gallons per day Watts Kwik Change reverse osmosis system. We also carry all of the genuine filters for the system in our store as a pack for your convenience. Change every 3 years. Usually ships within 24 hours. Excellent value. If you purchased your system from Costco, these are not the filters for your system, you want the ro-pure filters on our site.