I don't understand why people say stuff like this. I can fit my stark and A3 under my barbour coat. IIRC I've seen fitpics with Mellowfellow with a vest over his Inverallan and a Barbour layered over his 3A as well. some outerwear are more voluminous than others even if you size accordingly. My 3A is really not that much thicker than most SNS products I've owned and handled.