Yongnuo 1 x YN-622C-TX + 2 x YN-622C RX E-TTL LCD Wireless Flash Controller Wireless Flash Trigger Transceiver For Canon EOS DSLR The distance is 100m with 6 channels and the Max Sync Speed reaches 1/8000S. Can support TTL Ratio, USB Firmware Upgrade, AF Assist Beam Emitter. It has 3Groups (A/B/C) and Sync mode: 1st-curtain, 2nd-curtain, High-Speed Sync(HSS) Flash mode: GR(E-TTL(II), manual, Super Sync)/E-TTL(II)/Multi flash Weight 82g and shutter release interface is 2.5MM Shutter release interface