Professional JJC 3 in 1 Stacking Grid Light modifier System For Canon 580EX 580EX II Flash Speedlight The JJC Light Modifier was designed to produce 3 different size of light spread (Small, Medium and Large) when aligned and stacked two grids together, produce the smallest spots of light. Stack the small grid into the bezel to produce large size spots of light, for medium size spots of light just stack the larger size grid into the bezel. To insert a grid, align the grooves on the side of the grid with the corresponding alignment ridges on the inside of the grid bezel. Firmly push the grid into the bezel until it comes to a complete stop. To remove grids simply push it back out of the bezel.