Just like the beer koozie, Bladder Koozies insulate your Camelbak® reservoir or Hydration pack water bladder. These koozies help keep your water cool in the heat and prevent freezing in the winter. Insulate your water bladder reservoir before you put it in your pack or carrier.Camelbak 100 oz/3.0L MIL SPEC Antidote Accessory Reservoir Short 90854*Empty Reservoir Dimensions Length: 14 x 9 in / (35.56 x 22.86 cm) *Full Reservoir Dimensions Length: 13.5 x 8 x 2.8 in / (34.3 x 7.11 cm)Look for Us on YouTube.