The centre of these fins flexes outwards to fit people with broad calves and large legs. So, if you have large legs and/or broad calves the fins will still fit you. They wrap around your shin to match your leg shape. You can also slide them up or down your leg for the most comfortable fit. You just need to check which fin strap length you need to fit you. The straps go around the narrowest part of your leg, just above your ankle. So, please measure the circumference around this narrowest part. If this circumference is 20-40 cm (8-16 inches) then the standard straps supplied with the fins will fit you. If this circumference is larger than 40 cm (16 inches), then just select the option for longer straps when you order your fins.