This is a Lowel 20 Degree Honeycomb Grid for Prime 400 LED Light. Grids control spill light and tunnel it forward so it falls where you want it and keeps it from areas that you don't. The lower the degree rating of the grid, the more it tunnels the light.
A simple, plain notebook ideal for taking notes, making drawings, and recording other details. Additionally, appealing to photographers, the back cover is finished with an 18% reflectance gray coating for accurate exposure metering.