These shirts regulate your body temp.

Quantum Dry™ Base Layer Long Sleeve Quantum Dry™ reversible seamless base layer was created with high tech nylon and polypropylene yarns. Technically engineered for superior moisture management and maximum breathability, this is an ideal first layer for skiing, snow boarding and running. When worn on the front side, the garment wicks sweat/moisture away from the body. When reversed, the garment repels water. * Reversible performance – one side wicks, the other side repels. * Nylon face is pill/abrasion-resistant. * Polypropylene face provides a smooth, next-to-skin feel. * Functional zoning - mesh zones under the arms and on the back provide ventilation, while embedded ribbing on chest, arms and kidneys provides additional support and stretch. * Limited seaming reduces chafe in friction zones and wear areas. * Semi-fit design reduces muscle fatigue when worn for extended periods (vs. compression fit garments).  $50   Learn More