Membrane Solutions Water Filter Straw 1500 Liters. Ensuring the safest water in the worst environments, the Personal Water Filter Straw has a four-stage filtration system What sets it above others is that the membranes have a pore size of 0.1 microns, filtering out 99.99 percent of substances The stages of filtration consist of a coarse filter screen, PP cotton, coconut shell activated carbon and hollow fiber membranes The straw is made out of food-grade, BPA-free ABS and has an attached cap on each end and comes with a neck lanyard The personal water filter straw is 6 7/10” long and 1” in diameter, weighs just 2 ozs, and fits in the palm of your hand