Yongnuo Speedlite Transmitter YN-E3-RT wireless flash shooting with a signal transmitter. Can control up to five groups (15 units) with the use of radio transmission for wireless multiple flash shooting function flash. Signal transmitter also has equivalent EOS-1D series camera dust and water droplets performance. 2.4G two-way radio communications wireless signal is fully compatible with the original ST-E3-RT / 600EXRT; 15 physical channels an automatic channel you can set as many as 10000 photographers ID professional occasions without interference; Farthest communication distance over 100 meters; Multiple YN-E3-RT can be shared using the same off-camera flash; Can display off-camera flash grouping Call Information; Firmware upgradeable via USB port; High-resolution dot matrix LCD screen backlit buttons; Dustproof and waterproof quick-locking mechanism; Built-in AF assist lamp buzzer; Wireless shutter control online shooting; ETTL / M / Multi / GR 4 flash modes; A / B / C / D / E of five flash grouping; Control up to 15 off-camera flash; Support for front -curtain sync rear-curtain sync (M mode) high-speed sync; Support ETTL light ratio exposure compensation exposure lock exposure bracketing modeling flash; 9 Custom Functions; Settings are automatically saved