Specification 

• YONGNUO YN560 IV Wireless Flash Speedlite Master +
  Slave Flash + Built-in Trigger System for
  Canon Nikon Pentax Olympus Fujifilm Panasonic Digital Cameras
  
• The YN 560IV speedlight took the 560III and introduced a built in controller as well.
  Now you can have it all in one nice package.
  Complete wireless radio signal control is built into the speedlight.
  Using this as a master flash you can control up to 3 groups of speedlights, 560iii or 560iv.
  You can make all the adjustment to the power output from this speedlight and
  it will send the information to the ones that you are using off camera.
  No need to walk over to make those adjustments.
  Portrait photographers, Real Estate photographers and more love this
  speedlight for its ease of use and its tremendous light output.

• Supports Wireless Slave Function
  Fully supports YN560-TX、RF-603（I/II),
  RF-602 Wireless transmitter One YN560 IV can respectively
  receive the wireless signal from YN560 IV、YN560-TX、RF-603 (I/II)、
  RF-602,with optional 16 channels; when the YN560 IV and YN560-TX used as transmitter,
  it can realize remote control the parameter settings.