What are these boards called?

[Tikka]

They have been on the ceiling of a bus I'm renovating, and I plan to put up the same/similar again. It is a thin sheet of some type of wood material, with a smooth white surface on one side. What are these sheets called?

Took some pictures to simplify a bit.

 

[Qlram]

Masonite?

 

[Tikka]

Searched a bit quickly and it seems to be masonite.
What do you think one should use for boards if you want to get under at least 90kr/m2?
I want it to be about as thin, but it doesn't have to have a smooth side.

 

[Nyfniken]

What do you think one should use for boards if you want to get below at least 90kr/m2?
I want it to be about as thin, but it doesn't have to be a smooth side

Masonite?

 

[MaxPax]

Humor at its best!

 

[gnejsarn]

Search for "lackboard" (masonit is sometimes called board) and you'll find many results. Bauhaus has it for 139 kr for 1220x2440, which is just over 45 kr/m2.

 

[Tikka]

Oops, I looked at the wrong thing regarding the price!
I accidentally looked at masonite for shelves I see now
Thanks for the answers!