YONGNUO YN600EX-RT YN600-EX-RT Auto TTL HSS Flash Speedlite with Radio Slave for Canon and Same as Canon 600EX-RT 1.Supports RT System 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. 2.Fully Compatible with YONGNUO YN-E3-RT,Canon's 600EX-RT/ST-E3-RT Wireless 3.High Guide Number, Supports High-speed Sync. GN60@ISO100?200mm;supports high-speed sync TTL, manual flash, Gr grouping flash, the highest synchronous speed can reach 1/8000s 4.Supports USB Firmware Upgrade The YN600EX-RT equipped with the USB interface, supports firmware upgrade, the users can download the upgrade firmware through the Yongnuo official website to upgrade the flash. 5.Supports Wireless Optical Slave function The YN600EX-RT supports YONGNUO, Canon's and Nikon's wireless optical master signal, supports S1 and S2 pre flash cancel mode. 6.Support Auto/Manual Zooming The YN600EX-RT supports auto and manual zooming, the flash coverage can be changed between AUTO, 20-200mm. 7.Settings Save Automatically, Supports Custom Settings (Fn) The parameters on the flash will automatically save when the flash turned off; the users can customize setting the flash function as needed. 8.Ultrafast Charging Recycle System, Supports External Power Supply 9.Equipped with Big Size LCD Display Screen, Standard PC Synchronous Interface Package including: 1 x Flash speedlite YN600EX-RT 1 x Mini Stand 1 x Manual in English and Chinese.