This Mizuno Breath Thermo Performance Shirt is meant to keep you warm on the course even when the weather turns cold. Breath Thermo Yarn is designed to trap escaping body heat to create warmth within the fabric. The fabric also is moisture-absorbing to manage humidity and defend against sudden changes in the external environment. Meaning even when temperatures drop or the weather changes quickly, you can stay warm and continue with your round. The fabric’s exothermic property allows the shirt to convert moisture into heat: the colder it gets, the warmer you will be.