The VOC120 is a surface-mounted, weather proof, speaker level volume control. It connects between the speaker outputs of an amplifier or receiver and a pair of speakers. The 1x setting allows the volume control to be used as a standard non-impedance matching control. The 2x, 4x, and 8x settings allow it to be used as an impedance matching control with up to 16 pairs of speakers and volume controls safely connected to one amplifier. Separate impedance matching components are not required. 1 inch PVC conduit connector.