This is a rare pin set. Not many of them survived or are compleet. This one is.
The city of Kaluga is known since 1371. These pins are made for celebrating 600 years of Kaluga so they are from 1971.
Kaluga is connected to Moscow by a railway line and by the ancient roadway, the Kaluga Road. This road offered Napoleon his favored escape route from the Moscow trap in the fall of 1812. But General Kutuzov repelled Napoleon’s advances in this direction and forced the retreating French army onto the old Smolensk road, previously devastated by the French during their invasion of Russia.
Also Kaluga is known for one of it’s most famous residents; Konstantin Tsiolkovsky. He was a pioneer in space research and invented the 3 stage rocket. So in Kaluga there is also a space museum in his honour.