RS-005
Three “Gooseneck” relays:
At the back, a J.H. Bunnell unit, with 20 ohms coils, more commonly known as a “Pony” relay.
Front row:
Left: This unit although of typical American design bears a “Walters Electrical Mfg. Co. Ltd. London 250 ohms” plate. It has differentially wound coils.
Right: a Signal Electric, 150 ohms relay.
The last two relays can be adjusted for sensitivity by moving the coils back and forward with regards to the armature.