Page Port Preamp/Expander boosts page port audio for up to 150 Valcom one-way speakers and serves as a master volume control. Additional Page Port Preamp/Expanders can be added for virtually unlimited system expansion. - Stainless Steel Hardware - Includes Surface/Flush Mount Box - Boost Audio Levels For Up To 150 Valcom Speakers - Add V-1094A's or V-2994-W's For Virtually Endless Expansion (150 One-Way Speakers Per Unit) - A Master Volume Control For Entire Systems Or Groups Of Remote Speakers - Pre-Amplified Low Level Audio To Remote Sites - Isolates Page Port From Speaker Lines - Input Impedance: 600 ohm; - 24 Vdc, 45 mA