Aquam Frntr Max Filter Sys Bkc PlusCustomize the MAX with any Series IV filter cartridge for use in emergencies, international travel, backcountry excursions or anywhere the water may be of questionable biological or chemical quality. The quick connects make it simple to plug into any hydration pack or inline system without a need to replace your current connectors. Plug in the patented bite valve to convert your MAX into a straw filter or gravity system. Features : Backcountry Plus