Iray ghost light kit classic is a collection of invisible lights that uses the original low opacity method of diffuse emission. Unlike modern ghost lights, these lights do not show up in reflections. The included lights are great for lighting large areas, and providing overall ambience, rather than direct key-lights which benefit from specular emission. If you have a large, difficult to light area, just one ceiling or flat ghost light can provide a base amount of lighting to work with. There are plenty of light strengths and emission colors included.