50 Roubles Heavy Tank ST-I

The ST-I (or ST-1) was a Soviet superheavy tank project developed in the late 1920s under the influence of British Vickers designs, though it never advanced beyond prototype stage. Whether the Soviet mint chose this obscure developmental vehicle over the more historically significant KV or IS series warrants some skepticism — this coin belongs to a commemorative series issued in the early 1990s as the USSR was dissolving, a period when Goznak produced numerous collectible issues partly to generate hard currency from foreign buyers rather than serve domestic circulation.