“Fit is spot on wearing only a T-shirt and the thermal vest attached, if you would want to wear a sweater or hoodie size up. I have the Plasma extended back potector insert and nucleon chest and the fit is still perfect for me. (94cm chest, size S). Great styling, reflective inserts, waterproof, and even has rubberised zips on the air vents so its easier to grab when on the bike. Great product!”