The Ameriphone HA-40 is a handset/headset amplifier made by Clarity. It will dramatically increase the way listeners can hear their callers. The HA-40 requires a 9-volt battery (included in the package). The amplifier will turn on automatically when the receiver is lifted or the headset is activated. It has a voice detection sensor allowing for automatic powering on/off control. Basically if the line remains silent for 10-15 seconds the amplifier will fade out into standby mode to conserve the battery life. As soon as any voice or noise is detected the amplifier will turn on again. NOTE : This product is extremely sensitive. When installing, begin with the volume lowered to zero and carefully adjust to the preferred volume. Feature Identification: The volume switch (A) will increase the volume 100 times, up to 40 decibels. The Boost button (B) will mute your microphone while boosting the listening volume for extra loud and clear conversations. To use the Boost feature press and hold d…