PAB 20 is one of the most popular 2-channel photoelectric amplifiers, being a multiplexed device, often used in combination with 2 sets of remote transmitters, as well as receivers from the series 100, 110 and 120. The 2 channels are independently operated of each other, benefiting from their own set of remote receivers and transmitters, while the multiplexing function facilitates the prevention of optical cross talk between channels.