The entire bag goes in your freezer overnight (12 hours) to activate its built-in freezable gel

the backpack cooler will be full frozen and ready to chill items for hours

Perfect for transporting healthy foods such as: dairy

hours spent at the airports or on planes as well as for outdoor sports such as hiking

Castelli Light Head Thingy Multifunctional Running The entire bag goes inPRODUCT FEATURES 100% polyester jersey for maximum moisture management Seamless continuous tube construction Sublimated graphic Summer weight Protects from the sun's rays or provides a little extra warmth on cool days Weight: 45g Colure : Silver Gray