From the manufacturer

Men's HeatGear Mock Long Sleeve

HeatGear is our original performance baselayer—the one you put on first and take off last. So we made it extra comfortable by wicking sweat and stretching so you can move no matter what.

• Tough, lightweight HeatGear fabric, with all the performance benefits of UA Compression
• Stretch-mesh back & side panels deliver strategic ventilation
• Updated ergonomic design keeps seams off high abrasion areas & increases durability
• Material wicks sweat & dries really fast
• Mock neck construction for added coverage