From Watch Wiki
Derived from the ETA 2892, the 2892-2 is extremely low-profile, measuring just 11½ lignes (25.60 mm) in diameter and 3.6 mm high. Due to this thin profile, the 2892-2 is often used as a base for other complications, including ETA's 2894-2 modular chronograph. Although the 2892-2 was only produced from 1983 through 2000, its components remain in production for the 2894-2 and others.
The 2892-2 is very similar to the common ETA 2892-A2, as both share a common base.