Base Layers fisrt became popular around the early 90s, and have really taken of since then. It has almost replaced the old style cotton long johns. The modern base layers will wick away sweat in summer and keep you warm in winter. First time buyers are surprised how they work so well. The base layers is a lightweight way to keep warm or as used as a top in summer for a wind breaker or insulating layer. Great for Military,cycling or walking. Helly Hansen have a superb range and we now include these at discount prices