This selfwinding movement is with 7 1/2 lignes very small, but rather thick. During it production in the 1970ies and early 1980ies, it was one of the smallest selfwinding movements on the market.
The difference to caliber 420 is unknown.
|Number of jewels:||21|
Nickel anular balance|
|Balance bearing / direction hairspring:||Clockwise|
|Adjust mechanism:||Hairspring key|