The Visual Echos FX2 Better Beamer Flash Extender will help increase the reach of the flash and increases the flash output by about 2 to 3 f/stops. It focuses and concentrates the output of the flash into a narrow beam via the fresnel panel that gets positioned in front of the flash. This allows shooting at greater distances and shooting with smaller apertures.
The Better Beamer is designed to be used with lenses 300mm and longer, and its rugged, injection-molded plastic side supports are attached to the flash head by a sturdy elastic "hook-and-loop" band. The rigid supports hold the Fresnel screen in place in both horizontal and vertical formats.
The FX2 version will fit larger flash heads, e.g. Canon 540EZ, 550EX, Nikon SB-25 and SB-26, Sigma EF 500 series, Minolta 5600. The measurement between the two attachment flaps is 1 3/4".