The cornerstone of 39layering39 designed to be the cornerstone of a cyclists 39layering39 system morvelo39s thermoactive jerseys can be worn in a wide range of situations and to suit prevalling weather conditions by themselves when it is cool with a base layer andor gilet when it39s cold under a waterproof when it39s cold and wet used with a base layer and under a jacket if it39s freezing the closed cuffs and close fit arms work like arm warmers to keep out the cold an