The Gruen 621 watch movement, which is believed to have been manufactured around 1955, is an identical counterpart to the Angelus 120 SC movement. While both movements were mentioned in Flume catalogs starting from 1957, the Gruen 621 continued to be listed until 1972, whereas the Angelus 120 SC was not. Additionally, the Official Swiss parts catalog exclusively includes the Gruen 621 movement even as early as 1949, suggesting that Lavina is likely the manufacturer. The Gruen 621 movement features manual winding and sweep second functions.