I am selling this item because I no longer need it. It was used to detect the sound of an intercom and notify someone in another room. It has a 100m outdoor line-of-sight range and 16 different melodies. It can notify you with sound only, light only, or both sound and light. Includes: Sound sensor transmitter: 2 x AAA batteries Light and chime receiver: 3 x AA batteries Operation has been confirmed. There is some wear and tear. (The cushioning stickers used to attach the sound sensor have been used.) Includes the instruction manual and screws. AC adapter sold separately. Please excuse the eco-friendly shipping.