This is a White Narrow Flood Intensifier egg crate for the Arri Studio Cool 4 fluorescent fixture. In addition to narrowing the beam spread to about 40°, it softens the quality of the light to give even less contrast between highlights and shadow areas. It also booststhe light output of the fixture slightly, to counteract the diffusion.
Egg crates are essential accessories for any lighting system. An egg crate alters the shape and intensity of the light output from your light fixture. Consider an egg crate as a painter would a brush, or a sculptor would a knife, or chisel.
An egg crate is a rigid, or semi-rigid plastic or metal grid that narrows the spread of light. The spread of light will be determined by the density of the honeycomb mesh, and the distance of the subject from the light. Unless specified otherwise, an egg crate mounted on a light fixture will limit the spread of light to 40° from the face of the fixture.