Able to produce clean, fresh tasting, odorless water in 15 seconds the Grayl Legend is designed to protect against waterborne bacteria and protozoan cysts.. . . . . Working like a coffee press, just fill the outer cup with water, press the inner cup with filter into the outer cup, and force the water through the filter. Filters 16 oz. of water in roughly 15 sec.. Carbon core improves taste and eliminates odor. Removes 99.99% of bacteria and 99.94% of protozoan cysts . Filters many chemicals and heavy metals that affect health, flavor, and odor. Flip lock lid for easy sipping. Outer cup, inner cuppress, and lid are all dishwasher safe. Compatible with all Grayl interchangeable filters and purifiers.