We were excited to find a new hydration system that solve many of the problems of older systems. The Hydrapak is constructed with durable FDA approved Polyurethane. It comes with a lifetime no-leak warranty. The top of the bladder closes securely with a sliding clip. The combination of the wide opening and the supple material makes it possible to turn the Hydrapak inside out for easy cleaning and drying. The Hydrapak bladder can be used with or without the hydration hose and bite valve.