Use with 100-225 W-S with 10,20,or 30 degree grid at 5-15 feet for superb hairlight effects. Grids are great but using a grid + diffuser gives softer,more easily controlled light in close-quarters portraiture. I love a 20 degree grid with this diffuser added and 2-way barndoors for beautiful,stripbank-like separation or hairlight effects with the added bonus control over spill and the flag effect of the barndoors keeping the lens free of flares.
Also used for for smoothly lighting backdrops,using 2 matched heads with 11.5's + diffusers.These are "essential" accessories for light control within the Speedo system.