Your own personal radiator! Features: The SixSixOne Core-Cooler PCLPs along with their special combination of fabrics create a two-stage cooling system keeping the user cool; Cools by evaporation, as water vapor is released around the upper body, the effect is an overall increase in energy and comfort to the wearer; As the water vaporizes away, the Core-Cooler loses weight but maintains it's full cooling capacity; The inner liner, poly-suede material gives a soft non-abrasive feeling and creates a heat sync against the skin, which rapidly cools heat radiating to the body surface; No need to refrigerate it! The Core-Cooler cools itself through evaporation; After initial break-in, soaking the Core-Cooler for 5 minutes will offer light-weight cooling power for a long race or all day ride; 10 to 20 minutes will cool for up to 48 hours; 1 to 2 hours will fully charge your Personal Radiator; A fully hydrated SixSixOne Core-Cooler will cool effectively for up to 5 days on a single soaking and still weigh in at only 1 1/4 lbs.; The ergonomic shape makes for a comfortable, "You won't even know it's there" fit!