With a zip neck that makes for easy ventilation adjustment, the men's merino wool long sleeve Icebreaker Apex Zip Bodyfit active base layer is a simple, natural, high performance cold weather base layer top. This shirt is made of Icebreaker merino wool which resists odor naturally so you can wear it for days or even weeks without washing it û maybe you already do that but with Icebreaker merino wool you'll get less wrinkled noses from your friends and family when you take off your jacket. Icebreaker Merino wool is perfect for keeping New Zealand high mountain sheep comfortable and happy, insulating to warm them in the winter, and breathing and wicking to cool them in the summer; merino wool works like this for you too. The lightweight material has ultra fine fibers so it feels soft and won't itch, and it resists static electricity build up so it won't cling. The men's Icebreaker Apex Zip graphic sleeve stripe inserts add an extra element of style to the warm base layer and the Apex Zip allows you regulateyour body temperature when you wear it by itself. As an added bonus, this shirt also offers excellent sun protection (UPF rating of 50+.)