ColdPruf Men's Authentic Dual Layer Long Sleeve Wool Plus Crew Neck Base Layer Top Two-layer engineering with Merino Wool, traps body heat between layers, resulting in chill-blocking warmth Drop tail and stay-put rib cuffs maintains coverage in various activities Tagless labeling and flat seems provide a smooth fit and extra comfort Fits loose on the body, generous cut for full range of motion. For best fit, wash before wearing Perfect as a base layer or on its own. Best for dressing with minimal layers in extreme cold and low to medium activity levels