The TBB-1 will boost talk battery and loop currenton single analog line extensions behindPABXÆs and electronic key systems. This ishelpful for powering line powered devices,such as dialers and emergency phones on lowvoltage and/or low loop current extensions, Modular connections for easy installationò Boosts talk battery voltage and loop currentò Use with optional higher voltage adapter to gaineven more talk battery voltage (see chart below)ò Automatic polarity correction during installation