What is this electrical device?
I'm going to go with... It's a smoke/heat/CO alarm relay. There are many different types and they all look different. This is quote from the Kiddie website "This module is only activated by a smoke alarm interconnect signal. The relay portion of this module can be used to activate auxiliary warning devices such as external bells and sirens, hallway or stairwell lighting. It provides isolated, (no internal connection to 120 volts AC) normally open, and normally closed contacts"