Platypus makes hydration possible and easy when you are enjoying the remote areas of the world and you need to pack light and efficiently. The Platypus bottles and reservoirs are flexible so they fit into tight spaces. They are lined with beverage-grade polyethylene so they won't flavor your drinking water with unpleasant tastes. The Platypus hydration system has a complete line of hydration products: insulated bottle holsters, easy-to-fill wide-mouth reservoirs, and sophisticated hydration packs for hikers and paddlers. The Platypus Big Zip II™ 3.0 Liter is loaded with smart features. Check it out! The Platypus Platy Bottle™ w/ Push-pull Cap rolls up so it doesn't take up any space in your pack. Perfect for backpacking or travel. The Platypus Water Tank™ 4.0 Liter is the largest flexible water carrier. It has a comfortable handle and corner spout for easy pouring. It packs small and carries plenty. Big Zip™ wide-mouth opening allows for no-hassle filling and cleaning.