My foot measures 10 1/4 inches, I usually wear a 91/2 womans wide, or 10 medium width. They are my go to brand! (To fix this issue, I will be trying o-rings soon and update this review with some statistics. Now it doesnt even work on that. I have an iPhone 7 Plus with an Otterbox type case and it fits fine. I am disappointed that this accessory has not lasted as long as I thought it would. The sole still makes them very wearable around the house after a long day on my feet. They started snug but have opened up a little bit. I purchased two Auledio 4-Tier Shoe Racks and I was surprised at how sturdy they are once put together. The Makita guide rails dont come with connector bars, so youd still have to factor in that additional cost.