Main features:

1, Battery  compartment on alarm  top surface, battery replacement is very convenient;
2, Could be installed in motor homes, ships etc. quavering places;
3, Advanced photoelectric sensing technology; detects visible particles (associated with  smouldering fire) sooner than ionization alarms
4, Auto  check  malfunction.
5, Test  button;  tests  unit's  electronic  circuitry,  buzzer  and  battery  function Sensor type:

Technical specification:

Power supply: DC 9V battery
Standby current: <12µA
Alarm current: <10mA
Alarm sound: >85dB (3m)
Sensor type: Photoelectric
Battery life after low battery warning: >30days
Temperature range: 0°C ~ 49°C (32°F ~ 120°F)
Humidity: 10%~90%RH (No icing or condensation)
Dimension: Φ95x41mm
Executive  criteria:  EN14604:2005; GB4715-2005
Detecting  area:  80m  at  6-12m  installation  height;  60m  at  installation  height  <6m.

Instruction:

This product is a battery operated photoelectric smoke alarm, adopting unique structure design and advanced photoelectric sensor technology, able to monitor and detect smoke particles in real time.
Especially detects visible particles (associated with smouldering fire) sooner than ionization alarms. Once smoke particles or a fire danger is detected, this alarm will chirp and the red LED will flash rapidly to alert you and your family timely. Furthermore, this alarm has dustproof, mothproof and anti-light interference etc. functions, ensuring stability from design basis and  suitable for early warning and protection of fires in houses, factories, shopping malls, hotels, office buildings, school buildings, banks, libraries and warehouses etc. indoor places.

product pictures: