Buy from Amazon : br br YONGNUO YN-622C-TX E-TTL Wireless Flash Controller for Canon br br The distance is 100m with 7 channels and the Max Sync Speed reaches 18000S br Can support TTL Ratio USB Firmware Upgrade AF Assist Beam Emitter br It has 3Groups ABC and Sync mode 1st-curtain 2nd-curtain High-Speed SyncHSS br Flash mode GRE-TTLII manual Super SyncE-TTLIIMulti flash br Weight 82g and shutter release interface is 25MM Shutter release interface