I have to thank for giving me AMAZON proposed wired remote control because it is not mentioned anywhere, not even in the customer feedback, the only way to trigger the flash 580 EX II remote is normally buy in addition, the transmitter 220 CANON uros + its battery to 20 uros + battery special charger 40 or 50 uros nearly 300 uros more! This Wired shutter 30 euros allows me not to spend 10 times more for remote radio control, even if it CANON brand. Hence my THANK YOU, first at AMAZON I have proposed, then EAC for me to have sent timely. PS: I tested auto, semi-auto, ect. : IT IS FULLY COMPATIBLE!