Single headed tube, also known as single ended electric heating tube or cartridge heaters, is a type of electric heating tube (tubular electric heating element) that has been known for a long time in China's electric heating industry as the M3 model. In the late 1990s, due to the widespread use of electric heating tubes in China, the shapes of electric heating tubes also became many. In southern China, the electric heating tubes used for molds with one end output were called single head tubes or single end electric heating tubes, which were very similar.
In foreign countries, it is called a cartridge heater, which is also a figurative term. Because the shell of the cartridge is cylindrical and one end is also blocked, it is a clever coincidence with the Chinese saying that it is called a single end tube.