YONGNUO YN-622C-TX Wireless TTL Flash Controller Transmitter for Canon About the product 1. 3 groups (means that you can control up to 3 flashes that has YN622C attached). 2. Mix TTL, remote manual, and super sync groups 3. Individual 13rd stop manual power and FEC adjustment 4. Remote flash zoom in 3 groups, and auto zoom 5. 2nd curtain sync, HSS, super sync 6. USB port for firmware updates 7. AF assist light 8. Remote shutter release function (there is two cables to connect the unit to your camera) 9. Dedicated buttons for fast adjustments 10. Battery level indicator 11. PC sync port 12. 7 channels 13. Improved stability and transmission speed 14. Super sync manual timing adjustment by group (for supporting some studio flashes). 15. Flash value lock function (FVL) 16. Modeling flash & red-eye reduction flash 17. Settings saved automatically 18. PC port input 19. Up to 100m range 20. Basic trigger mode for non Canon cameras (with standard hotshoe, max sync speed is 1250s)