This  Nalgene 32oz wide mouthbottle design appears simple but is a super durable bottlethat is guaranteed leak proof.Graduations help you keep track ofyour fluid intake or serve as a useful guideline when mixing up abeverage in your Nalgene.Most backpacks have a pocket on the sideto hold a bottle and those pockets were designed to accommodate aNalgene bottle because hikers have trusted Nalgene for over twentyyears.