Yongnuo RF-603 Single 2.4GHz Wireless Flash Trigger/Wireless Shutter Release Tranceiver for Canon Cameras Includes (1) Transceiver only for Canon Transceiver System - works as a wireless flash trigger or receiver Each RF-603 is designed to work as trigger or as a receiver Compatible with Canon 1D/5D/7D/50D/40D/30D/20D/10D/300D/350D/400D/450D/500D/550D/1000D cameras