The top strap on the Amsterdam sandal is not flexible and the inside where the studs are cut both my feet.  My skin sticks to the leather in hot weather and there is no stretch in the sandal.  I loved these but had to give them away after wearing them a few times.  They turned out to be perfect for my sister in Ireland who has received many compliments on them.  I also own the Ibiza (classy) and Electra.  The Electra is super comfortable and my favorite.  Thank you FitFlop!