ERCO downlight reflectors are calculated using complex computer programs. This results in the reflectors having consistent cut-off angles for a variety of lamps and aperture sizes. Within the cut-off angle there will be no disturbing glare. This is the characteristic feature of the ERCO Darklight technology. The Darklight technology combines maximum visual comfort with maximum light output ratio and an exceptional balance between horizontal and vertical illuminance.

The standard cut-off angle of the ERCO downlight range is 40° this is the angle between the horizontal ceiling surface and the diagonal from lamp to reflector edge. The standard range is complemented by downlights with 30° and 50° cut-off angles.