The receiver has two output jacks so you can operate two launchers, bird releasers, or other compatible training devices from each receiver. One jack is on the left side of the receiver; the other is on the right side. (Left and right as you hold the receiver with the antenna pointing up and the control switches facing you.) The location of the left jack corresponds exactly to the location of the output jack on our older 150 System receivers, so the Pro Control® G3 receiver should be physically compatible with any training device you have operated with a 150 System.