The Lifestraw Flex Lifestraw Flex is a filter for backcountry use that removes lead and heavy metals. Flow rate isn't great, probably about the same as a Sawyer, and the one I have seems to clog kinda easily (they do include a syringe for backflushing). Like the BeFree it isn't rated for as many gallons as the Sawyer (4000L or 1000 gallons per their site), but it is lightweight and can fit on water bottles and such.

http://www.lifestraw.com/products/lifestraw-flex/