Right I really don't know how to explain it any simpler. The rubber lip is merely optional. When it comes out of the box, the lip is lowered. It is to do with controlling the amount of suction at the cleaner head. It means, unlike any other vacuum, the rubber lip creates a much greater seal, concentrating the SUCTION more so on carpets. Using the DC41 MK2 on hard flooring with this lip lowered means it is very difficult to push, which is why you can raise it. It also means large debris will fit underneath the head rather than being pushed around. My Felix and just about every other upright pushes cat litter and larger debris around. Raising the lip stops it. It even works on carpets. If you are picking up a mess on carpets, like rice, as you can see in the video I had the lip lowered, as you would usually use it when vacuuming, but because I was picking up large particles, I raised it and the snow ploughing stopped. It is a genius idea and one that works and of course, dyson patented it. I asked about it.
I appreciate dyson patenting their ideas, because, some of you may cringe when I say this, some of their designs are genius, like the tangle free turbine and active base plate. It means when one pays a lot of money for a dyson, they are investing in cutting edge technology in these aspects, its what makes it a better vacuum. And before anyone thinks I am made or over exaggerating, it is funny that when the patents run out, like dysons dual and multi cyclonic systems now have, other manufacturers where immediate to use the same principal in their vacuums.
I also still find it most amusing how people can come to an immediate conclusion that this is still just a pathetic overpriced dyson when they haven't even seen one in flesh, let alone use one.