I do not understand the sizing. Do you order you shoe size?
GREGORY H Yes, and I think they're men's U.S. sizes, but sized on the smaller side. I ordered the largest I could and they're still too small. I normally wear size 13 shoes.
BIO H Yes, you order by shoe size. They do not have all the sizes listed. I think they must be out of stock on the ones not listed.
Rafa S I'm in Mexico, & the sizing is different than in USA, but according my experience you can buy your fins based on your shoe size.
WILLIAM W I found that I needed to go one size larger than my normal shoe sizing. They tend to run a little small.
GRAHAM F I wear a 12 (wide, though) and the 2XL is perfect. It takes a tug to get on, but sits without squeezing my foot.