Get it wrong and you have a massive hole in the roof of your van.
I'm still waiting for mine to be fitted but a few months back went and did a tour of a few converters near me that all offered different style of roof. Only then did I feel informed enough to make what I believe to be the best choice that suits us and at a company that we think have a lot to offer. Seeing the guys fit a roof to another van was a bit like choosing a nursery for a child, you wanted to know it was going into a safe cared for environment,