At 170 lbs, it's very unlikely that he has a 16" neck. I used to buy size 16 shirts before I joined SF. Now I wear size 15. is 5'10 170lbs skinny? I'm 15lbs lighter and an inch shorter and I wouldn't call myself thin. Anyway, my neck measures 15.5" under my adams apple.. should I be sizing down? The neck on my CT shirts fit snug already so I doubt it..