THE DRT-4G 4 CHANNEL RADIO TRIGGER SYSTEM IS DESIGNED FOR PHOTOGRAPHIC STUDIOS AND ON LOCATION PHOTOGRAPHIC WORK TO TRIGGER YOUR STROBE/FLASH. IT WORKS WITH ALL OF THE STROBE/FLASH UNITS THAT WE SELL. THE TRANSMITTER FITS ON YOUR CAMERAS HOTSHOE AND THE RECEIVER CONNECTS VIA THE SYNC CORD OUTLET TO YOUR FLASH. IT HAS A REMOTE DISTANCE OF  APPROXIMATELY 35FT.  REQUIRES 2 AAA BATTERIES, NOT INCLUDED.