RS-006
At the back:
Left: Relay/Sounder of typical British design, maker unknown.
Right, marked: “Bunnell & Co. Inc. New York N.Y. Relay Type 2-1 500 ohms”.
To adjust for sensitivity the coils can be moved back and forward with regards to the armature. This relay is described in the Bunnell catalogue as “C.Q.A” (Champion Quick Adjustment).
Front: “1872 Edwards” relay presumably of American origin.
Coils, armature and contacts are vertically mounted.