This Impact Diffuser Sock is a heat-resistant (see note), 22" nylon fabric light softener ringed with strong elastic for a snug fit around metal strobe head reflectors. In addition, it is also ideal for use with 20 and 20.5" diffusers. The diffuser softens the light output and reduces it by 1 stop.Diffuser Socks are stackable, offering the opportunity to increase the diffusion effect while reducing the light output.Note: Intended for use on flash heads or fluorescent sources. Do not use on continuous hot light sources.Diffuses and softens the light output by 1 stop