This is indeed a one of a kind armored vehicle. I think that only a single prototype was ever built. After some successful tests of Grille artillery in the Italian Front a decision was made to test a Flak 37 on a heavily modified Panther chassis. I think it even reached the prototype stage.
When you open the box you will find more plastic than for the average model, as all the parts for the Flak 37 are provided by Dragon Models and the chassis, armored sides and running gear is provided by Bronco. There are over 60 sprues and two small photo-etch frets.
Instructions are very clear, probably CAD line drawings generated from the actual CAD design for the molds. The overall surface detail is outstanding, as the accompanying pictures show. Detail is not limited to the armored vehicle as you also get tarps, bags, helmets and rifles but not figures are provided.