Hydration is important, which is why most Osprey packs come with a hydration sleeve. But if you're planning to head into extreme environments you need a bit more in order to keep your water drinkable, like the Osprey Four Season Insulation Kit. Designed to keep your reservoir, hose, and bite valve protected from extreme cold, this is sure to keep water flowing freely even when the temperature drops below freezing. If you're heading out on a hot day, the bite valve cover is removable, making it easy to keep your water cool even when the temperature soars.

• Heat-reflective closed-cell foam construction offers maximum protection with minimal weight
• Attachment points make it easy to secure your reservoir in the sleeve, and the sleeve in your pack
• Bite valve cover zips of for summer use