Product review (4 stars): and they are all pretty much the same (except for the one's people actually ...
May not be "certified" as highly as name brand, but certification is expensive.  I suspect the inside of all of them is just an activated carbon filter, and they are all pretty much the same (except for the one's people actually complain about.) (I haven't cut one open to look).  Housing isn't as fancy or heavy, but it works and doesn't leak.  No taste or odor problems.  Just a filter, lots cheaper.