Next up in the layering process is the mid-layer. So put on your base layer and then get the mid layer ready. TOBE's merino wool mid layer is made to keep you warm and dry even in the coldest of climates. The shirt has 70% Merino wool and 30% polyester, the mix makes the shirt durable and warm. The Merino wool transports sweat from the skin to keep you dry and warm.