The Quell Q301 Series Bedroom/Hallway Smoke Alarm is designed to install in bedroom and hallways. Photoelectric sensor helps in detecting visible particles in smouldering fires. Sensing chamber makes use of a beam and a light sensor to detect slow burning fires. In case of a fire, the chamber changes the amount of light that touches the sensor and the alarm starts when the smoke reaches a threshold level. Hush button mutes unwanted noise and false alarms. Test button tests the circuit of the alarm and resets the memory after the alarm.