A replacement for when your original AC filter has done its mileage.Katadyn says:Filters up to 1000 liters, depending on water quality. Works with all BeFree Systems (42mm) except Gravity versions.Our VerdictThe Katadyn BeFree AC Replacement Filter Cartridge is designed to drop straight into your existing BeFree setup when your original unit reaches the end of its life. It keeps your filtration system running smoothly, especially if you filter water with noticeable taste or odour. Weighing just 33g, it threads onto standard 42mm BeFree soft flasks and can also be used with other compatible bottles like CNOC. Do note that this is just the filter cap; the activated carbon cartridge itself is sold separately.- Reviewed by Ultralight Outdoor GearFeaturesFlip CapSpecificationsWeight: 33gHelp & advice:The Ultimate Guide to Water Treatment and PurificationTime-Saver Guide to Water Purification

A replacement for when your original AC filter has done its mileage.Katadyn says:Filters up to 1000 liters, depending on water quality. Works with all BeFree Systems (42mm) except Gravity versions.Our VerdictT