Questions about Philips 5000 series DST5020/21

In the dark "droplet field" at the tip, there are 6 closed and 4 open vapour nozzles. The open ones are ground so that they steam towards the tip. The closed ones are too close to the outer edge. If they were all open over the entire base, there would be too much steam mixed with water. That would make a mess. The many open and closed ones result in much better gliding properties. Like a kind of indirect air cushion.