Tatco Visitor Arrival/Departure Chime, Battery Operated, 2-3/4w x 2d x 4-1/4h, GrayPleasant “ding-dong” sound alerts employees when visitors enter or exit. High/low/off adjustable volume control. Light-reactive sensor has sensing distance up to 15 ft. Wall mountable with angle-adjustable mounting bracket (included). Can be used with door open or closed. Color(s): Gray; Width: 2 3/4"; Depth: 2"; Height: 4 1/4".