Product review (3 stars): Spotty quality but price makes it worthwhile
Noticing that these are 1/3 the cost of GE's brand, I tried ordering one for my DIY-hacked undersink filter.  It was very difficult to align (kept getting water hammer), and the water was still very cloudy even after letting it run for two hours (it's supposed to clear within 5 minutes).

Spotty product quality comes with the territory of cheap.  It still might be worthwhile if less than 50% of units are defective, given that you're still ahead if you just throw those away.  However, I would have been a lot happier if the seller had offered to simply send a replacement, rather than making me ship back a used water filter (which is full of water).  For what it's worth, the replacement, while still requiring several tries to get it to align properly, is working fine.