The Extron MLS 100 A Switcher is a compact, four-input stereo audio switcher. Inputs one through four provide unbalanced audio while an additional input is an active auxiliary line level mono audio input that can be mixed with any of the other four selectable inputs. When used with a TouchLink® Control System or MediaLink® Controller, input selection and volume control are easily achieved using RS-232 or the controller's user interface. Input selection can also be controlled using the MLS 100 A switcher's front panel buttons.