if you're 6'10'', most definitely the large. but if you're 5'10'' and you mistyped, i'd go with the medium. i'm 5'11'' and the medium fit me just about perfect out of the box. that said, if you have a longer torso, then you might want to go with the large. best thing to do would be to find a store nearby that carries the infinity and try one one. or, cause the shipping'd be free, you could order one, then exchange it if the sizing was off.