The best way to learn about glow plugs is to experience them.

The Tower Power is very much like the OS two stoke plugs. They must be made by OS?

In the four stroke plugs the OS "F" and the Saito "SS" and the Y-S four stroke plug all look about the same. They run about the same also.

The standards of the industry right now are the OS "8" and OS "F". Other plugs are usually compared to them