Check the listing for details. Viking electronics TBB-1B Talk Battery Booster. Color: White, Condition: New. Listed at 107.51 USD. Viking Electronics battery booster and current looper to line powered devices Run line powered devices such as handsfree phones, touch tone hot-line dialers, digital announcers, etc. Increase maximum loop length on analog PABX/KSU stations Use with wireless doorbox devices Boost talk battery voltage up to 40VDC Boost talk battery loop current up to 26mA Power LED also displays activity Passes original ringing through to the device Passes caller ID data Passes hook switch flash Passes CPC signals Power adapter included Compatible with touch tone dialing Note: Not compatible with pulse/rotary dialing Power: 120VAC/12V DC 500mA, UL listed adapter provided Dimensions: 76mm x 112mm x 36mm (3.0” x 4.4” x 1.4”) Shipping Weight: 0.68 kg (1.5 lbs) Environmental: 0° C to 32° C (32° F to 90° F) with 5% to 95% non-condensing humidity Loop Current to Device: 26mA (nominal) Talk Battery Output: 40V DC (nominal) Connections: (4) screw terminals