Speed Grids attach quickly and easily to most portable flash units using our non-slip Speed Strap * 1/8 Speed Grid has a 1/8" honeycomb cell size to narrow the beam of light from your portable flash unit, producing a small circle of light * Fits most any shoe mount and most handle mount portable strobes, including Canon 420 though 580 and Nikon SB24 though SB900 * Attaches quickly and easily to our Speed Strap mounting system * Usable honeycomb area is 3.5" x 2.25" (appr. 89mm x 58mm)