Feel more at ease and secure knowing if a door or window in your home has been opened. The HA360DCDS transmitter works together with a Sonic Alert Main HA360 unit (sold separately) to send a wireless signal alerting you when a door or window has been opened. The HA360 Main unit will then flash a strobe, make a loud sound and vibrate an optional bed shaker. When the HA360DCDS is linked to a Main HA360 unit, it can alert you to 5 different possible scenarios, (DOOR, FTDOOR, BKDOOR, DOOR3 and DOOR4). The HA360 Main unit will also transmit the alert to all HomeAware remote receivers. When using an optional Sonic Alert Bridge unit, all original SA receivers (SA101, SA201, BL300 and SB1000) will alert you.