Beautiful appearance, stable function, loud and clear sound, suitable for use in noisy places. Easy to install, plug and play! No complicated installation required. Plug directly into a standard wall telephone socket Connect with the telephone line, no other power supply is required. It can help the hearing-impaired, sleepers, and those who like to stay away from the phone. The ringing amplifier is powered directly by the telephone line itself; it never needs any batteries or additional power to run. It will ring at a volume of up to 95dB, and as long as the phone rings, it will ring to get your attention and make sure that the phone is answered.