Opas for Canon, the flash remote control, is a group Transceiver (it can be used as Transmitter and Receiver). It can make flash and camera to flash synchronized, the off-camera flash can group control; It also has shutter function which can remote control camera to shoot and make the off-camera flash fire synchronized at the same time. With global free 2.4GHz channel, the product adopts FSK and has a stable performance.