The Valcom V-2992 Volume Control is a volume control unit which can be mounted into a single-gang electrical box. This unit is compatible with all Valcom one-way and two-way speakers. The V-2992 is not designed to connect directly to the output of high-powered amplifiers. -Features:-Control Volume Of Up To 150 One-Way Speakers -White -Applications:-To control volume of one-way amplified speaker assemblies in inaccessible areas -To control large groups of one-way amplified speaker assemblies -To control volume of Valcom talkback speakers -Volume control for Valcom V-1039A, Explosion Proof Horn