With a stretchy construction and flatlock stitched seams, the Kari Traa Lune Long Sleeve Top is one comfortable baselayer for all of your athletic activities. The fabric is designed to breathe and vent moisture when you're working hard, keeping you dry and warm throughout the day. The Lune is a supremely versatile active layer for four season use, with a slim fit that layers nicely under a midlayer and shell.