Review on EnviroCare Replacement Filters Progressive Machines by Shannon Hernandez

Even if you have pets, this filter won't stick together after a year. They help reduce dandruff and other pollutants from vacuum cleaner exhaust, but they're not 100% "clean air". I used to think HEPA meant the air coming out the back of the vacuum was like "cleaned air," but that's not the case. Like a good oven filter, it traps more pollutants; enough to notice the difference. Most importantly, change your bag (or consider using HEPA bags) often enough so that you don't have to worry about the filter. They say you should change it once a year I think which is probably reasonable if you have a few pets. For those that don't, I bet these things will easily last 18 months unless you live in a very dusty/very high pollen/mold house.