For our Snø base-layer we have used our favorite yarn from Südwolle, the Nm 1/60, 100% super fine merino wool, 17,5 microns, and added some Creora-Eco-Soft, to make the fabric stretchy. It's a single jersey that's light and breathable. Feels like a second layer of skin. This long-sleeved t-shirt has flat lock seams for better comfort, and a fitted shape.