The compatible Osprey reservoir insulator (also called a hydration bladder sleeve or reservoir insulation sleeve) is a specially designed cover that wraps around your Osprey water reservoir to help regulate the temperature of the water inside. Crafted from durable, lightweight neoprene material, this water bladder insulation adds an extra layer of thermal protection inside your hydration backpack. It’s easy to slip on and secure, and is compatible with popular Osprey reservoirs as well as other major hydration systems. Built to maintain your water bladder system’s performance across a wide range of weather conditions, it helps keep drinking water cool in hot climates and helps prevents it from freezing in cold environments.