This product is now more like an actual jersey that I feel comfortable using on 60-68 deg F days alone, down to 45-50 depending on base layers used. Looks good and bright for dull winter months. So I bought three Mediums in different colors.Bought a Large last year but it ran big - can fit plenty of base layers and have some air too! THAT ONE was not really a "jersey" - more of a jacket with heavier construction.