Cold weather, warm weather?whatever. Our Merino Sleeveless Tech Layer is going to keep you dry and comfortable over the long haul. The science behind it is pretty simple. The base layer is comprised of a blend of synthetic, hydrophobic VaporRize? fibers and Merino wool yarns that are naturally hydrophilic, meaning that thye love pulling moisture away from the skin. And when they do this, our blend of fibers distributes it across a large surface area where it can be rapidly evapora..