You've never worn a Merino base layer like this. We use a unique fabric construction method to place polyester fibers against your skin to improve wicking and Merino facing the jersey for temperature regulation and odor control. The 18.5-micron Merino is responsibly sourced while the polyester is spun from recycled water bottles. The polyester also increases the base layer's durability. The short sleeves feature a set-in construction for a versatile next-to-skin form fit.