OSD Audio SVC405 is a 300-Watt impedance-matching volume control with two-source (A/B) switching that allows you to adjust the volume of a pair of speakers independently of other speakers and control the volume of two pairs of speakers and one audio source. Ideal for both home and commercial installations, this decorative in-wall volume control includes an impedance-matching feature that stabilizes the ohm load so parallel connections of multiple volume controls can be installed without damaging the amplifier. The SVC405 maintains the full hi-fi audio frequency response with no low frequency roll-off and is rated at 300 Watts per channel (100W RMS). The rotary knob adjusts the volume from inaudible to loud, and when you order the SVC405, you get the complete kit that includes the junction box, screws white trim plate.