The Terramar Helix baselayer is great in colder weather to keep you warm and dry but that same technology works great in the summer as a lightweight endurance shirt. Whether you're going for a late afternoon trail run or going for a new personal altitude record in the mountains, the Helix Mountain tee with Terramar's ec2 Qwik-Dri technology will work hard to keep you dry. Even if you get caught in a sudden rain storm, as soon as the sun pops through, your Helix Mountain tee will dry fast so you can get back to enjoying the outdoors in comfort. Weeklong backpacking trips and 100 mile ultra-marathons are no problem for the Helix Mountain tee. Anti-Microbial treatments are woven into the fabric to keep your shirt fresh even after extended use.