Detector 43RML100 is a multi-criteria detector combining the detection modes of the rate-of-rise detector 43RCS000 and the optical smoke detector 43RFU000, and is therefore particularly suited to applications where early fire detection must be ultra-reliable hotels, museums, etc. The detector triggers the alarm if the smoke or temperature threshold is exceeded; plus, if a sharp rise in temperature occurs, the smoke detection sensitivity is set to its maximum level.