Berezin B-20
Berezin B-20 is an aircraft artillery or autocannon.
Also recorded as B-20; Berezin UB-20.
Overview
20 mm autocannon aircraft armament.
In detail
It is associated with Soviet Union.
Sources
Each source is named with the standing the house places on it, so the evidence can be weighed rather than taken on trust.
reference work · Reputable secondary · Wikipedia
“Berezin B-20”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q819083: Berezin B-20
Consult the source