The SG-N Light Modifier was designed to produce 3 different size of light spread (Small, Medium and Large) and 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. Attaching the Grid to your Flash: 1.Attached the Light Modifier to the flash head just imply put the flash head into the Light Modifier Flash Bracket, 2.Screw the grid mount and flash bracket together then stack the grids you need into the bezel, 3.Screw the bezel to grid mount until it comes to complete stop