For double sizes, so as is here by the seller, it is not easy to determine the appropriate size class. I had therefore lead me from the experiences of other buyers leave (s. Reviews) who recommend the tendency for these water sports shoe a (double) size larger. In my shoe size of 41 so I opted for the double size 42/43, but which turned out to be significantly oversized when trying on clothes. Since me the shoe convinced of his appearance, the material and the apparently very good build quality, I do not ordered as a supposedly suitable replacement 40/41, but which clearly too small failed which then ultimately did not surprise me, because the sole stamping (40) consistent with the label on the shoe (40/41). Thus, the confusion was perfect and met my needs for further Anprobierübungen. 5 stars for the article, not be spoiled for choice of size.