Those trendy American sports sunglasses from Goodr are characterized, among other things, by the various frames they make. Each frame has its own width and with that, Goodr comes in three sizes. 

Measuring glasses is quite difficult. What we can do is give an average. If you have a small head, you take an S. If you have an average head, you take an M and if you have a large head, you take an L. Each model only comes in one size. Below you can see per model whether it is very wide or very narrow.