Here's the blurb from the manufacturer:
A bright orange light flashes when the phone is ringing.
Perfect for the hearing impaired.
Also very helpful in noisy rooms and for those rooms that need to be quiet.
This bell ringer amplifier has 2 different options to select from:
* Flashing light only
* Loud ringer with flashing light
Use it directly to a phone jack and between a wall jack and a phone.