Yongnuo 2pcs Yn600ex-rt 2.4g Wireless HSS Flash 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/t2i 500d/t1i 450d/xsi 1100d 1000d Dslr Camera Lamp Illumination The YN600EX-RT can be used as on-camera master unit and remote slave unit of Canon's RT system,and supports Gr grouping mode. Fully Compatible with YONGNUO YN-E3-RT,Canon's 600EX-RT/ST-E3-RT Wireless Signal GN60@ISO100200mm;supports high-speed sync TTL, manual flash, Gr grouping flash, the highest synchronous speed can reach 1/8000s The YN600EX-RT supports YONGNUO, Canon's and Nikon's wireless optical master signal, supports S1 and S2 pre flash cancel mode. The YN600EX-RT supports auto and manual zooming, the flash coverage can be changed between AUTO, 20~200mm.