Essentially a short-sleeve jacket, or a fully wind and waterproof jersey, the innovative Xenon GT AS Jacket from Gore Bike Wear is the first of its kind; a champion of thermoregulation that offers the best of a number of worlds. Firstly, it provides the superb packability and core weather protection of a vest, with the added shoulder and underarm weatherproofing of a jacket. The elimination of sleeves below the elbow let you maximize your efforts without the fear of overheating. It also holds better shape than a vest and is thus easier to pull on at the apex of a climb, when it's time to begin your downward charge back below the thermocline. Wear it as a second weatherproof jersey, or stash it as a backup when the weather turns—the choice is yours.