This Transceiver Radio Slave for canon is a combination of both a transmitter and receiver. This PocketWizard has High-Speed Sync Technology provides an auto flash with camera's shutter speed up to 1/8000th of a second. It's channel 1 and 2 settings come programed, however you can adjust to any 20 ControlTL channels for TTl photography. The FlexTT5 is also ideal for manual flash photography where you can also pick between 32 standard channels. Slide this piece of equipment right onto your camera's hot shoe for easy access.