Yongnuo YN560 IV Speedlite Flash Supports Wireless Master Function *The 560 IV can be used as master unit, provides 3 independent groups with controlling ability, realizing remote control the flash mode, flash output and focal length of the YN560 IV and YN560 III. *GN58 @ ISO100105mm *Sound Prompting System *Support Electric Zooming Function *Supports Wireless Slave Function, fully supports YN560-TXRF-603I/IIRF-602 Wireless transmitter