Gamma Cool Band

Holabird Sports

On changeovers, you can put a wet towel around your neck to cool down, but on a hot day it'll become a lukewarm rag in no time. Instead, use the Gamma Cool Band. It is filled with polymer crystals that transform into cold, soft pellets when soaked with water, and they stay cold as long as the band remains wet. Washable, it should last you the summer before it needs to be replaced.