Product review (2 stars): Not so good product and so good service.
I bought 2 packs of 2 filters (trying to safe money). It fits in the slot.  But it was very hard to twist it in to lock. It was so hard that I had to use plyers which broke the end filter's holder. I want to return 1 pack. It has been 10 days, and I still waiting for the returning slip.