Our cooling technology was selected after exhaustive testing of ice, gel, and phase change cooling packs. Only one technology proved superior and could meet our demands - and that technology is incorporated into every garment we design. Colder than ice, gel, or other phase change Longest lasting Lightest Articulated Non-toxic / Food safe Reusable How to Activate & Use Scrunch cells vigorously in a basin of warm water Let CoolPaks soak and continue to absorb water. Activation is done only once! Lay plumped CoolPaks into freezer until ready to use Refreeze and reuse repeatedly How long will Your CoolPaks stay cold? In low-humid environments, you can expect a maximum of four (4) hours before your CoolPaks will expire. Headbands and Gloves will stay cold up to 2 hours. High humidity can cut cooling time by as much as two hours. Most people order a second set of CoolPaks to extend their cooling time - or simply to have another set ready to cool at a later time. When will you need to replace your CoolPak set? You can use your CoolPaks over and over again, but at some point in time they will need to be replaced. People who depend on cooling only during summer months could enjoy as many as four years with their CoolPaks. People in warmer climates may have to replace their CoolPaks sooner - particularly if a backup set is not put into rotation. What does it mean when your CoolPaks soften? As your CoolPaks absorb your body heat, they will soften. But they will continue to provide cooling even during this phase change! Adaptation is what happens when you "get used to" the cool temperature of your CoolPaks. It's similar to what happens when you jump into a frigid swimming pool, then feel comfortable after 30 minutes. The easiest way to determine if your CoolPaks are still doing their job - is to place your hand on your skin beneath your vest. If your skin is still cool, your CoolPaks are still working. Features: Longest lasting Lightest Articulated Non-toxic / Food safe Reusable Oro Sports Ultimo Coolpaks - Size Youth