The HydraPak Flux+ 1.5L Water Bottle with Built-In Filter is a collapsible bottle with built in filter for safe, easy hydration in the backcountry. Fill from the source and drink directly from the bottle, or squeeze the bottle into various other containers. The built-in filter features hollow fibers, effectively removing common waterborne bacteria such as E.coli and parasitic cysts. When the bottle is empty, roll it up and secure it with the strap to save space inside your pack.