They're 50mm. Pretty much as advertised, they are a good compromise between the 58s and the 38s. The build quality is very good, they have stayed very true and I have hit some big holes and just today went over a wooden bridge that shook my teeth out without the wheels going out of true. IME they are fine in the wind.

The only issue I have had is with the freehub not engaging consistently. Taking it off and cleaning out the grease / oiling it helped, but it still skips once and awhile after coasting or shifting. I guess there are other hub options coming.