Krown Ringer Amplifier with Strobe Light - The hearing impaired signaler monitors a telephone line for incoming calls and flashes the bright strobe light to alert the hearing impaired that the phone is ringing. This hard of hearing signaler features an extended louder ringer, up to 120 dB. The unit has two controls for the ringer; one that controls loudness and another to control the tone for a customized ringer. This hearing impaired device easily connects to, and is powered by, your telephone line. Strong strobe light is operated by the included AC adapter and a battery backup (requires 3 AA batteries, not included). One year manufacturer's warranty.