Answer the following question: Question: What does the factory containing the "secret German Spy Post office" make? If there is no answer, please output "Insufficient information to provide an answer.". Movie title: Secret Agent Context: Soviet intelligence officer Aleksey Fedotov by the name of Heinrich Eckert departs for German occupied Vinnytsia. His purpose is to obtain the secret correspondence of General Kuhn with the Hitler's headquarters. When his radio operator, sent to Aleksey, is executed, Fedotov is forced to search for a contact through the local underground, but accidentally he discovers that one of the underground workers is a provocateur.
Answer:
Insufficient information to provide an answer.