"I wear an 8.5 M width and usually have a rough time finding shoes that fit my narrow heel and high arch. These are perfect :) There is no gap between my heel and the shoe so my feet don't slip out - which is usually an issue for me - nor do they rub uncomfortably against each other. As for my arch, there is no squeezing or pinching. I have worn them for extended periods of time with no discomfort. I bought the black/white combo, but I would love to get the other color as well."