Yongnuo RF-603C3-INT Wireless Remote Flash Trigger for Canon 1D 1DS 5D 5DII LF23

Works as a wireless shutter release control to trigger your camera
Transceiver System – works as a wireless flash trigger and receiver
Each RF-603 is designed to work as trigger and as receiver
Compatible with Canon 1D/5D/7D/50D/40D/30D/20D/10D Series cameras for shutter release control