The Tatco Visitor Chime TCO15300 features a pleasant 'ding-dong' sound with high-low-off volume control. It includes a light-reactive sensor with a sensing distance of up to 15 feet, allowing it to be used with the door open or closed. The chime mounts easily on the wall with an angle-adjustable bracket and operates with 4 AA batteries or the TCO 16300 6V DC adapter (sold separately).