Carbon heaters are medium-wave heaters with carbon filaments inside a quartz tube. Like quartz heaters they have a relatively low radiation efficiency of around 60% and the rest of the energy is used warming the air. Throw is limited, and heat transfer is a mix of radiation and convection. The wavelengths of infrared produced by these heaters are not absorbed into your body very well, but they will make the surface of your skin feel hot. It is wasteful to use the outside or in large/tall buildings. We do not sell these.