Jaeger-LeCoultre Caliber JLC 657 Watch Movement

Manufacturer	Jaeger-LeCoultre (JLC)
Calibre Number	657
Type	Quartz
Jewels	4
Frequency	32,768Hz
Battery Cell	SR616SW
Hands Count	2
Functions	Central hours; central minutes
Country of Manufacture	Switzerland, Swiss made
Known Models	Reverso Classic Small 261.81.30, Reverso One Reedition 325.84.70, Reverso One Cordonnet 326.44.20 (Add your watch to the comments below…)

The Jaeger-LeCoultre caliber 657 is a Swiss made in-house quartz movement found in smaller ladies sized Reverso timepieces. Such model have made use of this caliber since at least 2016 (source).

Additional Resources: