Original YONGNUO YN660 Wireless Flash Speedlite GN66 2.4G Wireless HSS 1/8000s for Nikon Pentax Olympus camera YONGNUO YN660 Wireless Flash Speedlite The YN660 is built upon the previous YN560 IV, now providing 6 groups in the Radio Master mode, up from just 3 previously, as well as boosting power output to a Guide Number of 66 meters (ISO 100, 199mm), Other improvements include 24-199mm flash head zoom, lever locking foot, and updated buttons / main control dial. It supports Yongnuo's full 2.4GHz manual flash control system. YN660 can act as a wireless master flash for the previous-generation Yongnuo YN560 III and YN560 IV flashes, and as a slave (with remote adjustment) to the YN560-IV YN660 and Yongnuo YN560-TX RF-603 II RF-605 RF-602. Crucially, you are able to control up to six groups of flashes. Suitable for: Suit for All Standard Hot Shoe DSLR Camera, such as Canon, Nikon, Pentax, Olympus. .Except some Sony cameras (It needs hot shoe adapter to use the flash) Compatible slave flash / receiver units include -YN560 IV, YN-560 III, and YN660 flashes. RF-605, RF-603 II. Compatible transmitter / master flash units include -YN560 IV, and YN660 flashes. YN560-TX RF-605, RF-603 II. RF-602 With the YN560-TX tranmitter, and YN560 IV / YN660 flashes providing the most functionality, including Remote Manual Power and Flash Head Zoom Control. 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 YN660,YN560 IV,YN560III. Supports wireless slave function, fully supports the YN660,YN560 IV,YN560-TX,RF605,RF603(II),RF602 wireless transmitter One YN660 can respectively accept the signal transmitted from the YN660,YN560 IV,YN560-TX,RF605,RF603 (II),RF602 wireless transmitter,with 16 channels for option; when the YN660,YN560 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.