Most fuel powered radio controlled cars and boats are powered by glow fuel, which is ignited in the engine by a glow plug. These are similar to a spark plug, but due to the compression style of combustion in the engine, they are only utilized in starting the engine. Glow plugs usually require a 1.5-2volt supply to light them, and so most people would use a rechargeable glo start to power them. These glow supplies are manufactured in varying capacities, giving you more or less starts between charges. The higher the Mah of the glow start, the greater the number of firings you can expect from it before it needs to be recharged. All glow plugs come with a standard thread fitting to the engine, and also a standard sized hexagon head for removal. A glow plug spanner is essensial for fast removal of plugs when the need comes to replace them.