From Watch Wiki
The 2894 is unusual in that it is not derived from the Valjoux 7750, which is the basis for most of ETA's chronograph movements. Instead, like the ETA 2094, the 2894-2 is a modular design pairing a traditional base with a self-contained chronograph module. In this case, the 2894-2 is based on the low-profile ETA 2892-2.
The 2894 is somewhat smaller than the 7750 family, measuring 12½ lignes (28.00 mm) in diameter and 6.10 mm high compared to the typical 13¼ lignes (30.00 mm) diameter and 7.90 mm height of the 7750 family.
Unlike the Valjoux, which can be serviced by a watchmaker, the 2894-2 chronograph module is only serviceable by the factory. Repairs typically consist of replacing the module entirely.
Mechanical movement with automatic winding, ball-bearing rotor, hacking seconds, small second at the "3", chronograph, date display at the "4" with quickset feature. It is sold by TAG Heuer as their "Calibre 17".