Universal Security Instruments MDS300 Iophic 9 Volt Battery Operated M Series Smoke / Fire Alarm with Ionization Sensor is designed to virtually eliminate nuisance alarms cause by non-hazardous sources such as every day cooking smoke or steamy showers. Nuisance alarms are the leading reason for intentionally disabled smoke alarms. Working smoke alarms are a key factor in surviving a fire. NEW IOPHIC TECHNOLOGY - Makes conventional alarms obsolete. IoPhic is an ionization alarm containing a patent-pending Universal Smoke Sensing Technology.