I bought mine online too, so I just guessed my hands might fall into the small/ medium size. I was right. I love them and now can't FMQ without them! They fit "like a glove"... pun intended
What I like most is that my hands don't overheat or get sweaty wearing them. They are breathable and comfy. I never noticed any smell from them, and I bought mine while I was pregnant, with a super sharp pregnancy sense of smell!