A classic midweight baselayer the Hot Chillys Micro-Elite Chamois Zone Men's Zip-T is a direct descendent of the first technical layer created back in 19840 talk about a synthetic baselayer that has stood the test of time! This fabric is the most reliable and durable made by Hot Chilly, its thermal success lies in the blend of enhanced polyester and spandex fibers which create a stretchy, wicking, breathable, fabric that keeps your core comfortable by trapping warmth and moving moisture to keep you drier. This zip tee is a technical performance baselayer built to glide smoothly into your midlayer, a midweight for winter, with thumbholes to keep the sleeves lying smoothly and bio-silver for odor blocking so you can stay fresh out there. And because we know you love versatility in your sportswear, this has UPF 30 sun protection for those spring days when you need to protect your skin from both a chill0 and a burn. A classic, super stretchy, high necked baselayer with a zip you can open up for venting if you need it, the ever desirable thumbhole loops in the cuffs, and an active stretch seam construction to minimize chaffing, no matter how active you get out there.