The Felsa 90 described here is one of the latest cylinder movements of a ladies’ watch and was probably made in the 1940ies or even 1950ies.
Originally, it was made by AM und had the same caliber number there, AM 90.
Its measured size is 19.6 x 12.6 x 4mm (= 8 3/4 x 5 1/2 lignes, although it was listed in the Flume K1 with 5 1/4 lignes) and it contains 10 jewels.
This movement used the patent DE652036 from AM, which describes the fast releasing mainspring barrel.
As you can see on the details, this movement was a bit reworked during the production time frame.
|Size:||5 1/4''' (measured: 19,6 x 12,6mm)|
|Number of jewels:||10|
Nickel anular balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Long regulator arm|
|Winding mechanism:||rocking bar winding system|
|Setting lever spring:||3 hole(s)|
Flume: 1947 46|