This is a Silver Medium Flood egg crate for the Arri Studio Cool 2 fluorescent fixture. In addition to narrowing the beam spread to about 40°, it intensifies, and "hardens" the quality of the light to give more dramatic shadows.
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.