Yongnuo 2xYN-600EX-RT 2.4G Wireless Flash Speedlite with YN-E3-RT Radio Transmitter Set Light for Canon 1dx 1ds III 1d 5diii 5dii 6d 7d 70d 60d 50d 40d 700d/t5i 650d/t4i 600d/t3i 550d Fully compatible with the original ST-E3-RT / 600EX -RT wireless signal,max Transmission Range:100M Support ETTL / M / Multi / GR modes and A / B / C / D / E groups (control up to 15 unit), automatic saving setting, 9 Custom Functions, 15 physical channels, 1 automatic channel, as many as 10,000 settable photographer ID, free of interference besides professional occasions Support functions: master falsh, high-speed sync, FEC, FEB, Rear-curtain sync, FE lock, auto zooming, Sound prompt system, PC sync, power saving, overheating warning, auto saving setting, advanced flash settings Support USB firmware upgrade, GN60@ISO100200mm, top sync speed up to 1/8000s,external power supply supported, speed recycling system Fully compatible to YN-E3-RT, Canon 600EX-RT/ST-E3-RT radio signal