To fire the Flash Speedlite One RF603II receiver can fire one flash speedlite, one set of RF-603II can control 2pcs Flash Speedlite at the same time.
Additional Function Adding the Locking rings. Improved Flash / Shutter control Buttons. Working for more non Canon/ cameras and single firing pin cameras. Auto-Focus, Continuous shooting, Long Exposure, Half-Way Pressing, Full-way Pressing and Bulb.