Background Music Input With Voice Operated Mute, Built-In Single and Warble Tone Generator, Phantom Zone Allows Paging To All Speakers But Limits Music To Selected Speakers, Page Override For Special or Priority Announcements, Battery Back-Up Input (VPB-260), Power Built-In, UL Listed; ACCESS: Page Port, PBX Loop-Start Trunk Port, Electronic or 1A2 Line Key (line card required), or Dedicated Single Line Phone Set; Specifications: Input Impedance: 600 ohm; Music Source Impedance: 4 to 600 ohm; Music Input Level: -10 dBm nominal; DC Output: -24 Vdc @ 1A; Power Requirements: 230 Vac/.5A; Shipping Weight: 5.3 lbs (2.41 kg)Dimensions: 7.01" H x 9.0" W x 2.4" D (18.03 cm x 22.86 cm x 6.12 cm)