This is a 40 degree egg crate grid for the Westcott 36" x 48" Shallow softbox. Grids are essential accessories for any lighting system to alter the shape and intensity of the light output from your modifier when mounted on a light head. Consider a grid as a painter would a brush, or a sculptor would a knife, or chisel. Use of an egg crate will result in a narrower spread of light. The spread of light will be determined by the density of the grid and the distance of the light from the subject. When mounted on a softbox, this egg crate will limit the spread of light to 40 from the face of the softbox.