Louroe Audio Monitoring PTA-1 Portable Test Amplifier is a battery operated audio amplifier kit used to conduct quality checks of microphone connections during installation and periodic field checks. It will work with a single microphone or at the output of a MLA-6 mixer/combiner. Contains a 2 1/2 inch speaker and 6 feet lead wires with alligator clips for testing connections. Two 9V batteries included.