The Honl Photo superior quality filters attach quickly to the HONL Speed Strap (sold separately), & can be used in tandem with the Speed Grids, Speed Snoots, & Speed Gobos. Usable filter area is 2.5" x 4" & can be trimmed with scissors to fit your individual strobes. One of the secrets of great lighting is that it's sometimes necessary to adjust the colour of your strobes to correct for colours in your scene or to add a creative effect. Many people rely on photo editing software or plug-ins to correct their images but it's always better to get a perfect image in your camera than it is to shoot an unbalanced or poorly composed scene & try to correct it later.