Simple and durable, the LifeStraw Peak Series Collapsible Squeeze 650ml Bottle with Filter weighs just over 3 ounces and provides runners, hikers, and travelers with a means to not only to carry water but to safely treat it on the go. The membrane microfilter effectively filters up to 500 gallons of water (depending on water quality). This handy all-in-one system acts as both storage and filtration. An internal hollow-fiber filter is 99.999% effective against waterborne bacteria, parasites (including Giardia and Cryptosporidium), microplastics, silt, sand, and cloudiness. No pumping is required and there is no need to allow time for purification to occur. Simply fill the flask, screw on the combination filter and cap, and squeeze for clean, safe water! For cleaning, a custom backwash accessory is included to avoid clogs and maintain a fast flow rate. All of the materials used in the filter and soft flask are BPA-free.The collapsible flask holds a little over 20 ounces of water and is made of durable materials for reliable performance during far-flung adventures. The flask cap protects against leakage and has a drinking spout for easy sipping. A smaller screw-top cap keeps the spout clean when not in use. There's also a carry hook for attaching the system to a pack.While designed to be used with the included soft flask, the filter has a threaded bottom that can be used with standard water bottles or other LifeStraw Peak Series systems (both sold separately). The LifeStraw Peak Series Collapsible Squeeze 650ml Bottle with Filter is available in your choice of colors.