The Pocket Wizard Plus III Transceiver is a radio triggering transceiver/receiver for remote firing of flashes and strobes. It can also be used to remotely trigger shutters with the appropriate Pocket Wizard motor cord (not included). It connects to your camera with either a sync cable (chosen at checkout) or via your camera's hotshoe. It connects to your flash or strobe by sync cable. Each Plus III is both a transceiver/receiver so they are interchangeable on your camera and strobe but you do need 2 PocketWizards for your off-camera strobe firing to work unless your strobe has a power pack with a built in receiver. This rental comes with only 1 Plus III. Two new AA batteries (not included) will run the Plus III for about 50 hours.
For more information on sync cable compatibility, see this guide.