This base layer harnesses a smooth, sweat-wicking fabric to keep you cool and dry on warm days. 360° degree stretch ensures long-lasting, unrestrictive comfort in the saddle, while ultra-soft seams with flat lock stitches eliminate bulk when worn under hoodies, jackets and fleeces.To stop you from getting too hot, there are underarm vents for breathability. And UV 50 protection keeps you safe when the sun comes out.