Unique easy-access impedance matching jumper setting without open the weatherproof seal box. If you enjoy an outdoor audio system, you'll love the convenience of outdoor volume controls! Now you can stop dragging the remote control outside where it is sure to get lost, or avoid having to get up and go to your audio source to turn the volume up or down. This pure resonance volume control offers 300 Watts of optimized sound quality with minimal bass roll-off. Control 1-8 pairs of speakers simultaneously with impedance matching. The autoformer design features outstanding sound quality due to high permeability steel utilization in the volume control core. Comes with Grey or white face plate. In addition, the OVC-300 includes an easy access impedance switch that lets you set the impedance without opening the box.