Bladder Insulators are compatible with Camelbak Hydration Pack Reservoirs Keep your water cool in the heat and help prevent freezing in the winter. Water Bladder Reservoir Insulation and Protection. Easy Installation. (Installation videos can be found on YouTube) See Size Chart Picture and READ description below to order correct size.****(Water Bladder and Drink Tube Cover NOT included)**** Veteran Owned Business and Made in the USA