This Columbia shirt with "Omni-freeze technology" (copyright) is supposed to be cooler than cool. http://www.outsideonline.com/blog/fitness/a-columbia-shirt-that-gets-goosebumps-to-cool-you.html
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OH BOY - more gear to buy!!Columbia says that bare skin is no longer the coolest option on hot humid days. The company’s newest creation, clothes made with Omni-Freeze ZERO, is, they claim, even cooler.
ZERO has circles of a sweat-absorbing polymer that swell and turn blue like tiny ice packs when you start to drip. The mechanical reaction (not chemical, as in cooling fabrics that use minty xylitol to provide a chill) sucks heat away from your body as well as moisture.





