2XU Aero 1/2 Zip. Black/Silver ReflectiveSoft and smooth coverage that can be worn on its own or as an extra layer, the Aero 1 2 Zip has a lightweight breathable mesh back and is easily adjusts at the neck and sleeves so you can stay comfortable as you heat up or cool down. FLEXIBLE VERSATILITY Raglan sleeves provide maximum movement and 1 2 zip design lets you adjust exposure to the elements to your liking with thumbholes at sleeve cuffs providing extra warmth and coverage on cooler days.