These are a simple but great fitting snorkeling fin. Super comfortable fit. If you have a super wide foot then this is not the fin for you.
Mens sizes are spot on but if you are a 9, The medium will fit better than the large !! If you are an 11 then a large will fit you better !!
Ladies, these are mens sizes. Here is the translation...
Size XS 3-5 is ladies 6.5-7.5
Size small 5-7 is ladies 8-9