GODOX TT685C E-TTL 2.4G Wireless Master Slave Speedlight Flashlight Speedlite for Canon EOS 650D 600D 550D 500D 5D Mark III Compatibility: for Canon EOS Cameras(E-TTL II auotflash) Flash Modes: E-TTL /M /Multi Guide Number: GN 60m(ISO 100) Recycling Time: Approx 0.1-2.6s Power Source: 4 * AA Alkaline or NIMH battery(Not included)