The Army helmet came with a camouflage cover. There are no markings on the cover showings it is actually Danish.
I found a website about helmet covers: http://www.matshelmets.se/nets.html
This picture shows the helmet with an original camouflage net. Personally, I don't think it is a good system, it is not easy to place the net over the helmet. The liner doesn't fit into the helmet anymore when the net is installed.
This picture shows a funny detail: they used an actual hand grenade pin to hold the rubber band to the net.