THE NORTH FACE Men's Outdoor Wear Ventrix Active Crew Think of it as a padded piste with stretch. I bought several for work, but I'm selling them because my body shape has changed. I'm selling them a little cheaper. Thank you. The insulation uses "Ventrix," a slit-filled synthetic fiberfill that offers excellent breathability and stretch. The slits placed in the shoulder area, where there is a lot of movement, open during exercise to promote ventilation and close during breaks to increase heat retention. The underarms are designed without insulation to enhance breathability. The outer fabric uses Pertex Quantum Air, which balances breathability and wind resistance, and the synergistic effect with "Ventrix" releases moisture, keeping the interior of the garment comfortable. The North Face Patagonia Snow Peak Helly Hansen Montbell