Always good to see nice deals on stuff.
I'll chime in for when someone really needs some serious filtration- I highly recommend General Ecology:
http://www.amazon.com/General-Ecolo...=2025&creative=165953&creativeASIN=B00AI91958
I'll spare the technical details which can easily be found, but on three separate treks into the deep bush this filter has saved our bacon when all the others were clogging or breaking down. Take your pick of major brands you can buy from REI (other than this), and I have seen them give up the ghost on extended 2 week treks. Once on the Maine AT in the buggy water of the 100 Mile Wilderness, and 2X out west in the southern Rockies when drought conditions left us with nasty, dirty water sources at most campsites. I think the light duty stuff is OK if your source is pretty clean. In my case, by the end of the hiking treks out west my General Ecology was the only filter still working, supporting water for several people. I had to backwash it a couple times to keep it flowing.