So, there's a few options in their product line up. What's the hot ticket, buy once, get everything you need, w/o getting a bunch of junk you don't, kit? There's just the filters, two bag kits in 4l and 2l (gravity jobs?), the squeeze filter kit, the point zero two purifier, the point one inline filter w/ quick connect, etc..etc..
I guess product two cover two scenarios - filter water for a group and/or solo needs.