YONGNUO 2pcs YN600EX-RT Master TTL Flash Speedlite for Canon AS Canon 600EX-RT With 2pcs EACHSHOT Diffuser 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 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.