MSR Sweetwater Microfilter Testing: Testing: Meets NSF protocol P231 for removal of bacteria (99.9999%) and protozoa (99.9%) from beginning to end of filter life in worst-case water. Fresh Tasting Water: Activated carbon core helps eliminate taste and odors. Easy to Use: Unique lever-action pump handle has a 4-to-1 mechanical advantage, Lightweight: Weighing just 11 oz., it's one of the lightest filters on the market. Compact: Handle folds flat when not in use for easy packing and storage.