Nielsen frame dimensions

[Pete_G]

I'm about to order some Nielsen aluminium frames, the one's I want are 50 cm x 50 cm. My question is, is this the outside or inside dimension? i.e. I have artwork that
will be 50 cm x 50 cm, will it fit the frame? I've tried googling around and can't seem to find a definite answer.

[PeterAit]

It's the dimension of what will go in the frame. The outer dimensions will of course be a bit larger.