The Silent Light Phone Sensor allows you to turn off your phone ringer but never miss a call. Perfect for when your baby is sleeping, when company comes over, or while watching a movie or enjoying a meal. Flashes a blue LED light when phone rings. 100,000 hours of bulb life will last for years. Simply plug it into a phone jack and place next to your TV, computer, etc. When the phone rings, it will flash and you will know to answer the phone.