I’m a comfortably fitting size L in all other clothes with a 34inch waist and 40inch chest. I bought a size L and this jacket fitted like a corset if I zipped it up I could barely breathe, the arms were tight that I couldn’t bend them and my hand started getting pins and needles from lack of circulation.
I’m a sporty person with an athletic build and I can only guess that Spidi customers are usually emaciated stick insects.