Are you having someone build the wheel for you? They should be able to tell you what you need.

I have ordered from Bike24 a couple times, have been very happy with the results. The shipping charge however at 20 Euros (to USA) was rather expensive, so I spent some quality time on their website to see if there was anything else I might want, since adding a few more things did not increase the shipping cost. I ended up getting a helmet rain cover, a compression stuff sack, and a few other things that are very hard to buy in USA.