I keep seeing these tops on surplus sites. They are called either Norwegian Shirts, British Army Norwegian Shirts, British Army Cold Weather Norwegian Shirts, Norgie or Norgy.
The product description, where there are any, are not very helpful (and are occasionally contradictory).
On some sites they look quite chunky like a fleece
on others, the look more slim line like a base layer
I am confused and I'm seeking enlightenment.