The First Ascent 3L Top Fill Hydration bladder's tough design ensures long-lasting hydration on any expedition. The large Top Fill mechanism allows for easy filling, cleaning and drying, while the Ionpure Antimicrobial treatment ensures bladder film and tube remain odor, mold, and taste-free. The expertly designed 'Bite Me' valve comes with a lock system to prevent water wastage. Never let insufficient hydration cause you to cut your adventure short again.