Group of four spark/maritime keys, from left to right:
U.S. Navy flameproof key marked “CMI- 26003A”.
Manufactured by the Moulded Insulator Co.
Spark key made by the Signal Electric Mfg. Co. Diameter of contacts: 1/4 “.
Also known as the “Standard Wireless Key”.
Spark key marked “Mesco” (Manhattan Electrical Supply Co.). Diameter of contacts: 1/4 “.
Key with 3/16 “ diameter contacts.
Underside of knob is marked “Dyna”, of French origin.