The warmest undershirt in harkila's lineup is the long-sleeve Härkila Base Warm Zip Shirt. It is a perfect midlayer in cold weather since it is constructed of a highly soft, warm, breathable, and naturally temperature-regulating wool blend. The undershirt features a high collar that may be fastened tightly around the neck or opened to the chest for cooling down.

The Härkila Base Warm undershirt is composed of a blend of 60% wool, 20% polyester and 20% acrylic. This makes it more hardwearing than a pure wool garment, and it will give you many years of wear. There is a terry finish inside for extra warmth, and flat seams for comfort when worn under your other hunting clothes. It features a high neck with a zip, to give you extra protection from the cold when zipped up, or to stop you overheating when opened down to the chest. There are thumbholes at the cuffs, which allow you to pull the sleeves down over your hands to keep the heat in.

Click here for sizing guide.