I never wear thong sandals because the thong is too irritating. I wanted to try a pair to wear on days when I have a pedicure. I usually wear an 8 or 8 1/2 wide (D). I thought the adjustable strap would be a good feature. I ordered an 8 wide and they fit perfectly. The length and width couldn't be any smaller and still fit me. I didn't have to adjust the strap. The thong is fabric and very comfortable. While there is no obvious arch support in the foot bed, the strap seems to provide some arch support.
The sole is fairly firm but still flexible and very comfortable.