Glow plugs serve the same function in model engines as spark plugs do in automotive engines. Like their larger counterparts, they differ in heat values. Glow plugs are categorized into cold, warm, and hot plugs, which vary in the length and thickness of the heating coil as well as the size of the coil space. Additionally, the choice of metal alloys (platinum-iridium-nickel) significantly affects the heat value and durability of the plug. Plug type: G5, application area: gasoline engines.