PocketWizard PWP-TR 801-125 PLUS II Transceiver - Black Fast 'plug-and-play' set-up times Auto-Sensing Transceiver Technology enables the Plus II to switch back and forth between transmitter and receiver modes Auto-Relay Mode wirelessly triggers remotely located cameras and flashes within a 1600' range of one another Four 16-bit, digitally-coded channels enable you to simultaneously trigger all of you lights at once, or isolate one group of lights from another Ultra-fast microprocessors enable trigger-response times as short as 1/2000th of a second