Some infrared cabin models have a Quartz and Magnesium emitter.

The Quartz (position I) heats up more quickly and in a more targeted manner than Magnesium (position II), while this one emits a more enveloping and intense heat. The Quartz emitter lights up when powered, contrary to the Magnesium.

If you have several emitters, you can use the advantages of two technologies at the same time, depending on switch position on each emitter (position I = Quartz, position II = Magnesium).

To help you, here is a detailed diagram: