This hand control box is used on many model locomotives. It is an ergonomic hand control with an integral battery condition indicator and horn and lighting switches which connect to the Horn Relay Board (HRB).
These relay boards are designed to control 3 or 4 relays from one of our hand throttles. It has a number of "break points" on the circuit board that gives it a lot of flexibility to be used with [e.g. sound] systems that require isolated switch inputs.