I go between an XS and S, and the S fits me perfectly! So I decided to give them a try and went out on the town from dancing to walking for a couple of hours. If they will be placed on carpet, its recommended to put a hard surface under them for sturdiness (we used a really thick piece of cardboard). it comes with three other sleeves that allow you use one mount on multiple bicycles. elieve these are a good, not great value. Best ear cleaners i ever used. I still dont know what happened. There is no warranty card. My 4 stars is price adjusted. 5B (usually wear 8 wide or go up one size to 8.