The best base layer you can get. The MHS 1/4 zip top bears a close resemblance to the combat shirts worn by Soldiers under their body armor. It's an extremely effective base layer built for maximum comfort in physically demanding situations. The trunk and underarm portions are constructed with a stretchy Merino wool blend (itch-free) - a fabric that will keep you warm, but breathes extremely well so you don't overheat and get soaked with sweat. The upper sleeves and shoulders bear A-TACS camo, one of the most advanced camouflage patterns available, available exclusively through Browning for hunting applications.