The caliber of the Fliegerfaust A was 20mm and the missiles weighed about ninety grams each. The Fliegerfaust A was a prototype model, and the production model Fliegerfaust B was the more common of the two. It weighed 6.5 kg and it was 1.5 meters long. The Fliegerfaust B had a total of nine barrels versus the four on the Fliegerfaust A and there was a two second delay between each rocket firing.
Fliegerfaust A: The first variant, with 4 barrels.
Fliegerfaust B: The second variant, with 9 barrels.
A few photos seem to confirm the existence of this weapon in 1945, whether or not it was ever actually fired in anger is unknown due to the lateness of it's introduction and thus lack of documentation.