I purchased three filters in anticipation of changing my filters ever 4 months. Since I put a filter in just before the order arrived, it was 4 months until I used the first filter. When it came time to put my third filter in... the o ring was defective and would not seat. I called to report it and because it had been a year since I ordered (three of them) they would do nothing. How was I supposed to know the third one would be defective? BAD CUSTOMER SERVICE AND DEFECTIVE PRODUCT THEY DID NOT STAND BEHIND. Order at your own risk.