Product review (5 stars): excellent job filtering ;  worth the money in spite of need to replace frequently
These filters trap large, small, and very small lint fibers very effectively.  I typically get 3 or 4 washes per filter while washing my old, lint-producing clothes (mostly cotton).  If you wear more synthetic fabrics than I do and if your clothes are younger than 30 years, you should get 1 or 2  more washes per filter.  Given the cost of rebuilding a septic system drain field, the filters are a bargain, and I wish I had started using them sooner.  Attach the filters to your washer's drain hose at the top one inch of the filter, letting the rest hang down.  Do not use the filters beyond the point where lint reaches the top of the filter.  You can see this visually.  If you wait too long, the filter pops off with water splashing in all directions.