If you haven't worn the shoes out completely, you should be able to find inside each shoe a tag with a upc barcode as well as a number. That number is the identifying number for the model.

You need to size up at least a half size. I wear an women's 8.5 and ordered a 9. Still too small. I have a very narrow foot and this felt too tight in the arch.

The model number of your shoes is typically located under the size and above the barcode on the tag. It will be a six digit number followed by a three digit number (Example: AQ3366--601). Find the model number on the box if the tag is missing.