The Under Armour Women's HeatGear Armour Long Sleeve is a popular choice for women's tennis base layer top. It is made with Under Armour's HeatGear fabric that keeps you cool, dry, and light during intense matches. The compression fit provides a locked-in feel and supports your muscles for improved performance. The long sleeves offer extra coverage and protection from the sun. This base layer top also features UPF 30+ sun protection and anti-odor technology. With its high-quality construction and performance-enhancing features, it's no surprise that it is one of the most wished for women's tennis base layer tops on Amazon.