Product review (4 stars): Like others have said
I cannot give it 5 stars because of the problem with the spring valve inside the mounting head. Like others have said, there are nubs on the top of the filter which activate a valve in the mounting head. I spent hours trying to sort out why the water flow was so slow. This is compounded because my refrigerator has another filter cascaded from the GE. Since I changed both filters at very same time it was a mystery. I even put back the old filters and it was still slow. I was pulling my head until I read the other reviews and installed a hose coupler gasket inside. I don't think it is the "right fix" but it works for now. Shame on GE, they need to fix this problem. If you don't want the headache, don't buy the replacement cartridges, replace the system or get another brand.