I owned a pair of this same model sandal and wore them for at least 4 summers and loved them - very comfortable, great fit, excellent quality. Eventually they did wear out, and I needed to replace them.  I ordered the same model and expected to be equally thrilled with them, but I am not.  The size guide says that a size 40 is US size 9 - 9.5, which is the range I wear, but they seem short, just not short enough to get the next size up, a 41.  They are tight across the instep. The straps can be loosened, but there is an elastic band across the instep, under the adjustable strap that cannot be adjusted. I am not happy with them at all and don't know that I will take them with me on a trip I am planning later this month.  Somehow, Ecco has changed the design of this sandal over the past 4-5 years, and not for the better for me!