The La Sportiva Ridge T-Shirt runs on Polartec(R) Delta(TM), a knit that pairs hydrophobic and hydrophilic yarns to pull heat and moisture away from the body as airflow increases. That mechanism keeps the shirt working harder the longer and hotter a hike gets, instead of just wicking a little sweat at the start. Reinforced paneling across the shoulders and back stands up to the rub of a loaded pack, so long miles don't wear through the fabric before they wear out the hiker. What Our Gearhead(R) Experts Are Saying:"I hiked a hot, exposed ridge with a full pack on and the shirt actually felt cooler the harder I pushed, not just less soaked. The shoulders held up too, no thinning where the straps dug in all day."