All infrared heaters have the ability to be tuned. The wavelength is inversely proportional to the temperature. That is to say, as the temperature goes up - the wavelength goes down. Electric heaters have an infinite ability to be adjusted within the temperature limits of the heater. This allows for more flexibility in matching the output of the heater to the product requirements.
Gas heaters have less turndown capability.
Below that point the heaters will shut off. Many people believe that the goal is to match the output wavelength of the heater to the absorption of the product. This is a good point to start, but it is not always the case. For most applications, either short, medium, or long wavelength heaters can be applied. Generally speaking short wave will heat, cure, or dry the product in the shortest amount of time.