The Assos EQUIPE ThermoBooster P1 uses a breathable Skuba textile that traps heat in a low-volume loft, then compacts down to the size of a rain jacket the moment the ride or the temperature heats up. A struzzoKragen collar manages the throat's microclimate without needing to unzip, so warmth stays adjustable without ever losing the aero, second-skin fit underneath. What Our Gearhead(R) Experts Are Saying:"I stripped this off halfway up a climb once the effort caught up with the morning chill, and it packed down small enough to disappear into a jersey pocket without throwing off my balance. The collar alone had already vented enough heat that I almost didn't need to take it off at all."