The German Wirbelwind, or as it was affectionately known to its crews, 'Kekdose' (Biscuit Tin) went into production in 1944, the turret of damaged Panzer IVs being removed and the open topped turret replacing it, armed with a quad 20mm AA mount. (The turret being open rather than closed due to the dense clouds of smoke generated by the guns when firing) It was considered by all to be a highly effective AA platform and though only around 110 were built, it was considered to be a highly successful design, both in air, and ground rolls.
Equipping many of the SS Panzer Divisions there was a constant demand for more Wirbelwinds, but the disruption of the German armaments industry due to Allied bombing ensured that demand would always outstrip supply.