The WS-600 water sensor can be used with the Control Products HS-700 HomeSitter and WA-700 WaterAlarm dialers. The unit can be combined with other water sensors to maximize water sensing protection in any location where water is unwanted. Sensor provides a dry contact closure which can trigger an alarm dialer. More than one sensor can be used on both the HS-700 and the WA-700 products. THIS WILL NOT WORK WITH THE FA-D2.