I wear women size 7.  I am skinny but I have wide feet.  The Tide sandal has excellent arch support. But the strap on the Tide sandal gave me blisters and what looks like eczema. I returned it and got the Wave sandal.  Same problem with the Wave.  The strap is cheap and rough.  The sandals are made in China.  I question the quality and sanitary condition of the fabric.