AO SmithReverse Osmosis Membrane Replacement for The AO-US-RO-MB-4000 - Not Compatible with SmartFlow Systems

It does fit with my out of production system, i’m glad because this filter is the only one replacement that I couldn’t find anywhere else. Now I could extended it along with the other cartridges

The media could not be loaded. There's mixed reviews as to whether this filter fits the pure Blue H2O system from Costco . It fit mine with minimal modification as others suggested. Just remove the triangle tab on top of the filter. I bought new filters for the system thinking they were the cause of the slow flow rate of water, in the process I discovered that my water tank was low on pressure and had to simply add air to the system through the valve stem. It fills up just like a bicycle tire. Worth checking while you're working on the system, you can find many YouTube videos on it. My system was due for new filters anyway and this was my only option left for the R. O. filter. Glad it worked! Hope this helps others as well.

For those that know, the Costco water filter Ro system has replacement filters that are very difficult to find. You can find the original ones but they cost an arm and a leg and often do not include this very filter which connects to the drain. That said, this filter alone tends to remain expensive no matter what variation you purchase. This one is shorter than the original ones from Costco but still does offer the same amount of filtration for the RO system

We love our filters from Amazon. They give great performance, and easy to replace. Good price!

I couldn’t find a stage 2 filter for my Brita RO system but I found out that if you take some pliers and break off that tab sticking up on it, it will fit and work fine.

just had to break off the little triangle part on top and it fit just like it should.

Unable to find an OEM membrane for my pure blue H2O system, and other reviews led me to believe that this one could be made to work. It is definitely not compatible, and I damaged the cartridge in an attempt to modify it so unable to return. lesson learned!

I used this to replace discontinued Dupont WFROM1000X reverse osmosis membrane. Must remove the triangular tab at the top of the membrane which snaps off easily and cleanly with pliers (see photo). After that, twist locks right in as the original did.