WVC 100E is a weatherproof stereo impedance-magnifying volume controller that connect between the speaker-level output of an amplifier, speaker selector, or a Niles VCS HUB8 distribution hub and your speakers. The WVC 100E is a impedance-magnifying (IM) volume controls. Unlike other brands, they have additional autoformer windings that magnify the impedance of connected speakers, while allowing all 12 steps to adjust the volume of the sound. Switches on the PC board select these windings.