The Nikon SU-800 Wireless Speedlight Commander functions as a Wireless Commander for SB-R200, SB-800 and SB-600 Speedlights units. Supports the Nikon Creative Lighting System (CLS) and compatible CLS cameras. Controls an unlimited number of Speedlights up to three groups. Offers 4 independent channels for competitive shooting environments. Provides wireless control up to 66 feet Built-in AF Assist Illuminator for critical focus in low light situations.