The all new, state-of-the-art, DB 100 is the only doorbell and intercom signalers that require no wires and can be installed in seconds. Unlike competing models, the DB 100 is not triggered by sound, so annoying false alarms are a thing of the past. Other advanced features include: selectable number of flashes (5 or 10), different flash code for front door, rear door, or intercom (requires additional sensor, sold separately), and a built-in chime for hearing members of the family (can be turned off). The DB 100 has a built-in outlet to flash an attached lamp and each sends a signal to all Sonic Alert remote receivers. Use additional transmitters (up to four) to be alerted at other doors. Optional DB100T needed for additional doors (sold separately).