The honl 18 speed grid is a honeycomb diffuser with a 18 cell size designed to produce a narrow beam of light from your portable flash unit resulting in a small circle of light concentrated on your subject designed to fit almost any hot shoe mounted flashgun and most handle mount portable flash units including the canon 420ex 430ex and 580ex series and nikon sb24 through to the sb900 it attaches quickly and easily using the speed strap mounting system available separately the usable