ETA Caliber 2640

Manufacturer	ETA
Caliber Number	2640
Movement Type	Mechanical, manual-wind
Lignes	7.75”’
Diameter	17.5mm
Height	3.5mm
Jewel Count	17
Beat Rate / Frequency	21,600 bph / 3 Hz
Lift Angle	53 degrees
Power Reserve	~40 hours
Anti-Shock Device	Incabloc
Balance Part #	721/2007
Hand Count	3
Functions	Central hours; central minutes; central seconds
Country of Manufacture	Switzerland, Swiss made
Known Models	(Add your watch to the comments below…)

The ETA caliber 2640 is a small ladies size handwound movement with 17 jewels and a frequency of 3 Hz (21,600 beats per hour).

2640 VS 2660:

There is a similar caliber 2660 with the main difference being that the 2660 has a higher beat-rate of 28,800 bph (4 Hz).

Parts Interchangeability:

Many components are interchangeable between the 26XX family of movements, but it depends on the beat rate and calendar complications, etc. For example, the complete balance (with regulator and Incabloc) for the 2640 is part number 721/2007, and the packaging also lists calibres 2641, 2648, 2650, 2651, 2657, and 2658. NOS packaging will cross reference the compatible calibers for the part, but you will want to double check before ordering from your watch parts supplier of choice.

Additional Resources:

• More ETA watch movements