Neewer CellsII-C High Sync Speed Wireless Flash Strobe Trigger Transimitter Receiver for Canon EOS Series Cameras,Witstro series Speedlite,Neewer TT520 TT560 TT680 TT850 Flash (2 Pieces) Single transceiverdesign, could be used as either a transmitter or a receiver. Super high sync speed up to1/8000s, meets the need of high sync photography. 16 non-interfering optionalchannels enable you to control multiple flashes synchronously. This kit includes two sametransceivers for hotshoe-mounted Canon EOS series cameras. Transmit frequency: 433MHz wirelessremote system