A Vital plug, made in Cleveland, Ohio. This is a rare primer plug with 1/2-inch pipe thread.
A series plug by Sudig Co. made on Dec. 12, 1914, in New York City. This type of plug allows the user to have two plugs in one cylinder.
An extremely rare Blake quick-detach plug. The wooden handle allowed removal without tools. This plug sells for $1,000.
A Rentz intensifier plug. The switch on the left enables the intensifier to be shut off after the engine is started, preventing the coils from melting. It was a wonderful invention, but didn’t last because in 1920 at $2.50 per plug, it cost five times more than other plugs.
The Breech-Block Ignition Co. of Torrington, Conn., made this quick-detach plug, the base of which stays in the engine.