Triopo TR-586EX Wireless TTL Flash Speedlite for Nikon D4 D600 D800 D7100 SB-900 Guide number: 56 meters (ISO 100, 180mm) Circuit design: Insulated Gate Bipolar Transistor (IGBT) Flash mode: TTL / M / FEB / Slave (S1/S2) / Multi Zoom range: 18mm, 24mm, 28mm, 35mm, 50mm, 70mm, 85mm, 105mm, 135mm, 180mm Wireless trigger: Wireless induction triggering