Quite strangly one (right) is bigger than the other. The opening is several inches wider. Both footbeds appear to fit the same but my ankle moves around more in the larger one...I like the smaller one better.These are warm with thin socks and so far (several weeks as my main shoe) waterproof and easy to walk distances in--walked 3 miles round trip in complete comfort.Overall very good but disappointed such a brand name at this cost would be inconsistent. I will hesitate before clicking buy next time with this brand...Of note, I purchased a pair of boots directly from Sperry. Both shoes fit the same but a 10 was incredibly narrow with thin socks. I returned those.