Scrims are lighting accessories made of small screen material like aluminum or steel in a frame. There are full and half scrims, half scrims cover half of the opening of the lamp and full cover all of the light, scrims are available in different densities most common are single and double. Single scrims decrease the illumination by a factor of two, and double scrims decrease the illumination by a factor of four. A green frame surrounds single scrims, and a red frame surrounds doubles. They can be used for finer control over the lighting in a scene.