The YN-E3-RT II Wireless Speedlite Transmitter for Canon from Yongnuo is a 16 channel, 5 group wireless triggering device with a 328' range. The transmitter offers E-TTL II/E-TTL autoflash, manual flash, stroboscopic flash, auto external flash metering modes as well as 1:8 flash ratio control.
Convenience features include flash exposure lock, AF beam focus assist, modeling strobe and 9 custom functions. The YN-E3-RT II transmitter will run for 10 hours of continuous use on AA/LR6 alkaline batteries. A power saving function shuts the unit down after being idle for 5 minutes to conserve batteries. The YN-E3-RT II also supports firmware updates to make it future-proof.