The Mens Smartwool NTS Micro 150 Crew is comfortable enough to wear alone on a warm day or as a second layer in cooler temperatures. This Microweight Crew was designed with a crew neckline and the flatlock seam construction was implemented to reduce unwanted chafing. With shoulder panels eliminating the top shoulder seams found in other baselayers, the NTS Micro 150 crew feels comfortable under the straps of a backpack. The Microweight Crew is made of 100% Merino Wool offering exceptional moisture control and providing soft and durable comfort. The Mens Smartwool NTS Micro 150 Crew should be a staple item in your closet that keeps you comfortable all year round.