Radio-frequency set triggers any 1 or 2 standard shoe-mount flashes from up to 85 feet away, and without concern about other cameras setting off your light. The remote flash can be positioned freely without any line-of-sight limitations. Any of 4 radio frequencies can be selected for trouble-free flash synchronizing without interference from other nearby devices. The transmitter mounts on a camera's hot shoe mount, or use it on a flash bracket with the PC cord that is included. Receiver holds flash on any tripod or light stand with 1/4 x 20" socket, or any bracket with a flash shoe and also accepts an umbrella shaft. Adjustment knob allows flash and receiver to tilt for precise aiming control. Transmitter includes a #23A 12V battery, receiver requires (2) AAA batteries.