Ensuring the safest water in the worst environments, the Membrane Solutions Personal Water Filter Straw has a four-stage filtration system. What sets it above other filter straws on the market is that the filtration membranes have a pore size of 0.1 microns, which can filter out 99.99 percent of harmful substances and improve the taste. Compared to the .02-micron filter straws out there, Membrane Solutions’ Personal Water Filter Straw maintains the optimum flow rate while maintaining the filtration accuracy. The four stages of filtration consist of a coarse filter screen, PP cotton, coconut shell activated carbon and hollow fiber ultrafiltration membranes. A long lifespan ensures it provides up to 1500 liters (396 gallons) of drinking water. The straw is made out of food-grade, BPA-free ABS and has an attached cap on each end. It has a smaller frame than others on the market, making it more convenient to use. It also comes with a neck lanyard for easy carry.