Access potable water anywhere. HydaPak's unique and versatile 28MM inline filter threads directly onto popular 28MM opening bottles and flasks and is equally easy to install in any of HydraPak's reservoirs and caps with a Plug-N-Play connect system. This versatile connectivity makes our filter a great backcountry water treatment solution whether you are squeezing your water from a Stow into another bottle, gravity filtering your water out of a Seeker or Pioneer water storage bag or filtering as you drink on the go from a Stow or HydraPak reservoir. 28MM THREAD COMPATIBLE: Easily thread the filter onto some of the most popular backpacking bottles and flasks including the HydraPak Stow 500ML and 1L and the 1L Smart Water Bottle PLUG-N-PLAY COMPATIBLE: Easily connect and disconnect the filter from the Plug-N-Play ports in reservoirs and caps FAST & SAFE FILTRATION: Removes 99.99% of E Coli & Parasitic cysts. Filters approximately 1,500 liters of fresh water at a rate of >1 L per minute In