Winner of Runner's World Gear of the Year Award. With the Katadyn BeFree™ Water Filtration System, you no longer have to worry about where your next drink will come from. Just fill up the flask and let the EZ-Clean Membrane™ do the work. Gently squeeze the flask for instant refreshment. Maintain the EZ-Clean Membrane™ quickly and easily for longer life and more enjoyment. Simply fill the flask with water, attach the cover and shake free the debris. Or, remove the filter from the flask and swish in any lake, river or stream. And when you’re ready to hit the road, the collapsible flask packs small to fit into tight spaces. Just smash, stash and go!.Hydrapak® Soft Flask is longer lasting, rugged, high-tech, flexible, BPA-free..No backflushing and no clumsy tools. Simple shake or swish the EZ-Clean Membrane™ in the water and be on your way..0.1 micron hollow fiber technology..For solo use..Suitable for cloudy water..Lightweight and portable..Flow Rate: 1 liter per minute..Tested to 1000 L, depending on water quality..Wt. 2 oz (58g)..Size: 9.1 x 2.8 x 2.8 in (23.2 x 7 x 7 cm)..