This “Grand Prix” movement from Buren is a pretty old form movement, probably from the 1930ies. It’s high quality can be seen on the stripes decoration and on the bimetal balance with screws. Bimetal balances were not often used in tiny ladies’ movements. They reduce the running errors, which occur due to temperature changes to a minimum.
An interesting detail is the missing color on the “R”etard/“S”low marking of the balance cock. What might be the reason?
|Number of jewels:||17|
bimetallic screw balance|
|Balance bearing / direction hairspring:||Counterclockwise|
|Adjust mechanism:||Long regulator arm|
|Size:||5 3/4 x 8 1/2'''|