The warmth you generate is retained by PrimaLoft®. This is a newly developed synthetic that works in much the same way as down, creating millions of trapped air particles that keep the heat in and the cold out. PrimaLoft® is highly compressible and incredibly light and has the added benefit of maintaining its insulating ability even when wet. What ever climate you are traveling to, if there's risk it might get cold, be certain to take your Thermoball Hoody.
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