The Speech Adjust-a-Tone is an amplifier that can be used with a phone, TV, radio or tape recorder. System includes control unit and telephone cable. One year warranty. Features: Amplifies 40-120dB Six adjustable frequency compensation controls for base, mid and treble range together with volume control Individual 3.5mm jacks for phone base, phone receiver, TV/radio and headphone Telephone cable included (TV, radio or stereo cable not included) Not compatible with telephones with an amplified receiver 5-3/4" x 1-1/2" x 1-1/2" Uses one 9V battery (included). Battery Eliminator HC-9VPA recommended for purchase at the same time for continuous power when 9V battery runs out.