I'm usually a 101/2 in tennis shoes and the fins are a 8-9(42-43). I've tried them bare foot and my big toe and 2nd toe rest outside the pocket, but don't go beyond the outer ridge that divides the foot pocket from the blade. Guess they'd work with a lycra fin sock, but probably not the neoprone boot. They're from a LDS and were used, so price is good and just wondering whether size is not going to be an issue. Really like the foot pockets and think barefoot is an option.