Product review (5 stars): Fixed water flow restriction problem
This was easy to install and fixed my issue with low water flow. This housing is essentially a cutoff valve in the water supply line that feeds the water dispenser and ice maker. When you remove the filter, it closes and blocks water flow to the refrigerator.  When you put a new filter back in, it is supposed to open back up and let water flow freely.  However, mine was not opening all the way, restricting water flow.  Eventually it stopped opening at all. The valve is controlled by a little button that is depressed by the filter when you twist it into place. In my broken one this button was only a piece of black rubber. In my new assembly, it was white plastic and resembled the tip of a Phillips screwdriver. It looks like the plastic tip eventually breaks off and all you see is the rubber gasket that sealed around the tip.

Before I replaced mine, I tested the housing to make sure it was the cause of the restriction. I disconnected the line from the housing where it feeds the refrigerator pump and tested water flow by letting it run unto a bucket. I of course had to first cut off water at the wall and then turned it back on. This tested water flow from the wall through the housing with the bypass plug in place (to eliminate bad filter as possible blockage). When I tested this the water flow was full at first, but went to nothing in less than two seconds. For comparison to what it should be I first tested water flow from the wall to the bucket. For me this was not needed, but would help others who have reduced flow rather than no flow.