Cool-beam reflectors are made of glass with a special multiple coating that makes them transparent for infrared radiation but not for radiation at the wavelength of light. They are made of glass and multi-coated in a special finish. In the case of cool-beam reflector lamps (dichroic lamps), a significant portion of the thermal load (approx. 1/3) is therefore released though the back of the Reflector instead of radiating into the room together with the light as in the case of normal reflectors made of aluminium, for example. This characteristic makes these lamps ideally suited for illuminating objects that are sensitive to heat. On the other hand, when they are incorporated in a luminaire due attention must be paid to temperature build-up behind the lamp.