Cascade Designs Platypus Big Zip SL 1.8L Hydration Bladder - The Big Zip SL reservoir is the most deluxe, off-the-shelf hydration reservoir system made. Every beautiful, taste-free feature is designed to make staying hydrated easy—starting with our new SlideLock™ closure. It ensures an easy, leak-free closure every time, opens wide for easy cleaning and makes a convenient carry handle. Next up is the film. It’s BPA- free, supple, super-durable and treated with our all-natural SlimeGuard™ antimicrobial treatment to keep it taste-free. You also get an ergonomic, right-angle shut off valve for leak-free packing and a quick-disconnect hose for easy filling, cleaning and swapping of packs.