In addition to the volume boost, the amplifier has several features that improve and enhance your listening experience. High Definition Sound (HDS) Technology eliminates virtually all distortion, echo effects and unwanted static. Digital Tone Enhancement boosts and enriches the speech frequencies that you can’t hear well, making difficult to hear words intelligible again. Automatic Volume Control optimizes sound level for superior listening comfort.

Patented technology enables the Serene Universal Telephone Amplifier to work with virtually all corded home or business telephones. Uses one 9V Battery (not included.) Optional AC adapter (sold separately). One-year warranty.