The pre filters were a huge disappointment. My analysis of this product showed that it didn't work as intended and ended up clogging the vacuum. The only positive thing I can say is that the filters are easy to install. However, the cons outweigh the PROS.The material is flimsy, and it constantly sheds dust particles into the air making it a nightmare for anyone with allergies. Save your money and look for a better alternative in the Home and Kitchen department..