Buffer-Expander Volume Control. Continuously variable attenuator. Drive up to 150 self-amplified speaker inputs. 100V, 70V, 25V, and page port level selectable input. Bypass trim control for emergency paging (12 dB of preset control over level of bypass announcements). Mounts in a single gang electrical box. Rugged and attractive stainless steel plate with engraved lettering. Easy and secure terminal strip connections. Two-Year Warranty.