Optical window and door contact for Homematic IP - for invisible installation This opening sensor with an optical infrared light barrier disappears unobtrusively into door or window frames with a minimum distance of 1.5 cm between the frame and the casement or door leaf. An additional counter-contact is not required. Two replaceable batteries ensure that the window and door contact can be used for about four years. Homematic IP alarm sirens can be triggered by the contact. If the door/window contact detects that the monitored door or window is opened whilst the alarm is armed, the alarm is triggered and, depending on the configuration, a push message is sent to your phone. You can monitor the doors and windows constantly from your smartphone via the app. The sensor can also be used for heating control. The linked thermostat reduces the heating power during ventilation so that energy costs can be saved. Features / compatibility - Homematic IP integrates the areas of indoor climate, secu