This smoke detector can be randomly expanded with separately available wireless module FRM-320 (75 17 68). A simultaneous alarm trigger at all connected smoke detectors is also possible with a tandem switch via cable. The functioning of smoke detectors should be checked at least every 4 weeks. In conventional smoke detectors, the test button is usually attained only with tools (ladder, chair etc.). This hazardous situation is avoided when using an EASY TEST smoke detector. The big EASY TEST testing switch can be easily & safely activated, for example: using a broomstick.