I ordered for my son for Christmas a Kettler desk together with the roller containers Sit On, delivery via Amazon, as always top. During assembly was a bit of trouble going on, everything was to assemble quite normal, but when attaching the right-cheap-looking wheels, which are simply pressed with force / violence on the metal substructure I had difficulties, there was nothing, where the wheel locks, but you it must plan kloppen ... hmmm this place equal to the interposed underbody out ... strange, is to supposedly carry 75kg, how can it be so, I am relying on it with perhaps a force of 30 kg and it breaks ?! So I had the day before Christmas Eve, enhance the part it myself from the bottom with metal plates. I myself weigh about 66kg .... had so yes thought I could sit on the Sit On so if I want to do something at the desk with my son, I do not trust me now, of course, because more than 40 50 kg of probably not tolerate. The desk Kids Comfort is great, but the container I would have saved prefer.