YONGNUO YN660 Wireless Manual Flash Speedlite GN66 2.4G Wireless Radio Master+ Slave for Canon Nikon Pentax Olympus GN66@ ISO100,199mm,high guide number 2.4G wireless speedlite,supports M/Multi/-- mode. Supports wireless master control function,realize six groups of light control YN660 can be used as master control unit,be equipped with six groups of independent grouping control ability, realize remote control the flash mode,output and focal length of YN660YN560 IVYN560III. Supports wireless slave function, fully supports the YN660YN560 IVYN560-TXRF605RF603IIRF602 wireless transmitter One YN660 can respectively accept the signal transmitted from the YN660YN560 IVYN560-TXRF605RF603 (II)RF602 wireless transmitter,with 16 channels for option; when the YN660YN560 IV and YN560-TX used as transmitter,it can realize remote flash parameter adjustment. Multiple flexible trigger synchronous ways,YN660 can be triggered through the camera,2.4G wireless triggering,S1 and S2 pre flash trigger avoidance. Supports automatically save settings and custom settings Fn,the parameters on the flash will automatically save when the flash turned off; the users can customize setting the flash function as needed.