From the manufacturer

Women's HeatGear Compression Long Sleeve

Comfortable enough to wear as-is, and made with sweat-wicking materials that keep you cool when using it as a baselayer, this women’s long sleeve shirt performs from the second you toss it on, to the second you take it off.

• HeatGear fabrics make it lightweight, keeping you cool without being bulky
• Compression fit that doesn’t stiffen up & leave you with limited mobility
• 4-way stretch material lets you move freely in all directions
• Flatlock seams prevent chafing, delivering a comfortable & distraction-free fit all workout long
• Compression: Ultra-tight, second-skin fit.