Obviously I have found that Revain does not have a reliable supplier quality assurance system as this product is deficient in several aspects. Firstly there are two layers of felt on the felt part of the filter, the holes on the two didn't match, secondly the holes were too small for the machine and thirdly they were cut too wide so I had to modify it to use these. Next comes the foam part of the filter, yes you can slide it in the car but this can cause airflow restriction. In addition the Shark appears to have a solid system as evidenced by the instructions on the tape on the felt detailing how to fit it into the machine, this was not duplicated by this supplier. When a manufacturer goes the extra mile and performs DFMEA and PFMEA analysis, the least you can do is copy it. Next time I will buy genuine Shark parts and bypass Revain.