Flash units produce a harsh light, even when you use it
with the little plastic built-in diffusers / reflector of the flash. To
work close to a subject, you might need to soften this light. Flash
diffusers are here to help. Flash diffusers not only diffuse the light,
they spread
the light as well. It reduces the maximum working distance between your
flash and the object. You can use this diffuser simply by fitting it in
the flash head direct.