ProMaster FL1 Professional TTL Flash - For Nikon Excellent Electronic flash for all Nikon DSLRs Choose the E-TTL/I-TTL mode for fully automatic flash or manual mode for total control Built-in wireless TTL and optical slave functions for the maximum flexibility in off camera flash Guide Number: 54m / 180' at 105mm position (ISO 100) Motorized zoom head automatically responds to camera zoom to adjust flash power level to subject distance