I bought these at Right-on about two years ago and really liked them, but I never wore them, so they're unused. They're listed as 24 cm, but the official size is M-L. The back strap has Velcro, so you should be able to adjust it slightly. Although they are unused, they have been stored at home, so please check the photos carefully and only purchase them if you are not concerned. The soles are wavy, so they seem like they would be non-slip.