This is an Interfit 30° Honeycomb Grid attachment for the front of Interfit Stellar (X/XD/Xtreme) monolights.
Grids are essential accessories for any lighting system. A grid tunnels the light output from your softbox when it is mounted on a light head. Consider a grid as a painter would a brush, or a sculptor would a knife, or chisel.
Honeycomb grids and "egg crates" are rigid, or semi-rigid. Fabric grids are hand-stitched, and collapse easily for storage or transport. Use of a fabric grid, honeycomb grid, or "egg crate" will result in a narrower 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.