As a perfect alternative to down, this new Cirrus synthetic insulation performs just as well, even if it gets a good soaking from an unexpected downpour. It dries quick and keeps the wearer's core nice and warm and is lightweight too. Vests are really versatile, offering quick core warmth and leaves the arms free for greater mobility when climbing and scrambling about. The Pertex Quantum outer fabric is used to add durability and wind resistance especially on cold, dryer days. The Altus Vest is slim fitting with elasticated arm holes and two zipped hand pockets, with one doubling as a integrated stuff sack. This vest is worth taking along too when there is a good chance of wet weather as it fits under a shell jacket with ease.