The DUO REFRESH Series is great for two reasons: It’s big, and it’s convenient. We mean big. Each bottle holds almost 1 Liter of your favorite refresher. We mean convenient. The DUO lid has a silicone straw on one side, a large twist-open drinking spout on the other and a built-in folding carrying ring. The DUO series bottles are BPA-free and colorful TritanTM and will hold enough beverage for all your big activities.