Specifications: Commander FunctionYes Remote FunctionYes Guide Number28m/92ft. (at ISO 100, 35mm zoom head position, in FX format, standard illumination pattern, 20?C/68?F) to 39m/128ft. (at ISO 200, 35mm zoom head position, in FX format, standard illumination pattern, 20?C/68?F) Electronic ConstructionAutomatic Insulated Gate Bipolar Transistor (IGBT) and series circuitry Flash Exposure Controli-TTL Balanced