Roof Top Overland did a great job of getting me the parts I needed when Prinsu didn't properly fulfill my order...even if the parts Prinsu sends aren't completely figured out.
Prinsu, on the other hand need to develop their product line better, I'll relate my experience...
Prinsu designs their rood rack for the Mercedes Sprinter to use the existing holes in the roof to mount their rack. They provide rivet nuts to be swedged into the existing holes, 8 each side and spacers of various lengths with bolts to match. The longest spacers go in the middle with the short ones on the ends. This causes the rack to mimic the slight arch of the roof-line and is a nice aesthetic. But, many vans come from the factory with roof rails installed and many others install after-market roof rails for which Prinsu now makes a kit with slider plates and bolts to accommodate this method of mounting the rack to the roof. However, using these parts the rack now sits flat on the roof and does not arch gently to match the gentle curve of the roof. No instructions come with the rack itself but those can be easily looked up on Prinsu's site but the only instructions there are for the original method using the rivet nuts, nut roof rails.
Long story short, I purchased aftermarket spacers and new stainless bolts to get the rack to look like it's supposed to because Prinsu doesn't provide the parts for that to happen.
It's a good rack and functional but you will need to be prepared to stand on your head to make it right if you have rails on the top of your van. And Prinsu needs to step-up their game.
We appreciate the feedback and shared your comments with Prinsu. Good to hear you are pleased with the finished product and thanks for your patience through the process.