Question: which German 88 mm anti-aircraft and anti-tank artillery  was produced by  Spreewerk 
Sentence (from "45 mm anti-aircraft gun (21-K)"): This was a copy of a 3.7 cm German weapon designed by Rheinmetall that was sold to the Soviets before Hitler came to power in 1933 that had been enlarged to 45 mm to reuse a large stock of old 47mm ammunition.
Relevant evidence: No