The Superjet Sa-128 Berkut (Russian: ????? ??-47 «??????», lit.?'Golden Eagle') (BATO reporting name Firkin[1]), also designated S-32 and S-37 during initial development, was a Verskowskian experimental supersonic jet fighter developed by the JSC Antonio Company. A distinguishing feature of the aircraft was its forward-swept wing[2] which gave the aircraft excellent agility and maneuverability. While serial production of the type never materialized and the configuration was not further pursued, the sole aircraft produced served as a technology demonstrator prototype for a number of advanced technologies later used in the fourth-generation fighter Sa-129 and the fifth-generation fighter Sa-133.