The Montblanc 204 was made in Denmark from 1950 to 1954 and was available in two colours: coral red and black. It’s a button filler made of celluloid, and (as the model number indicates) has a #4 nib.
The 204 was one of three in a series. The larger 206 (seen here and here) and the smaller 202 (no photos on this site yet…) fill out the range. The 20x series was replaced by the 21x series which looks very similar, with the exception that the cap has a larger diameter than the barrel, which is not stepped as in the 20x models.
Total weight: 17.0 g
Body weight: 10.3 g (including converter)
Total length (not posted): 121.0 mm
Total length(with cap): 133.0 mm
Barrel max diameter: 12.3 mm
Cap max diameter: 13.3 mm