The Door Transmitter from Bellman & Symfon is part of the Visit Smart Home System that helps you to keep tabs on your home. Just place the Door Transmitter close to your existing door chime, when someone rings your doorbell, the Door Transmitter will send out a radio signal to the Visit receivers. You will be alerted with loud sounds, bright flashing lights, or vibrations depending on the receiver you have. The Door Transmitter is a great alerting device to help people with hearing loss, hard of hearing, and deaf not to miss any visitors. With the recognition technology, the Door Transmitter can detect doorbell rings with most door chimes in the market, but the recording feature can also allow you to record the chime of your doorbell if yours has a unique sound.