Product review (4 stars): I didn't buy mine here but I have one of ...
I didn't buy mine here but I have one of these. I use it in my portable Base Camp washer. It floats on top and "scoops" up the lint and pet hair.

It does nothing in my Whirlpool top loader. The bag depends on getting "spun" by an impeller to work. A regular agitator oscillates, and it doesn't get to scoop up much of anything.

If you have one of the small impeller apartment size washers and you are having problems with lint, this is a godsend.