This optical smoke alarm from Ei Electronics is the perfect addition to any home security system. With a battery included and replaceable battery feature, you can rest assured that your home is safe from fire. The 9V power source ensures that the alarm will operate at its best, and the 85dB operating sound rating will alert you and your loved ones in case of a fire. The unit measures 10cm in diameter and 3cm in depth, with a weight of 200g. The white colour and photoelectric type make it a sleek and reliable addition to your home. This unit is sold as a single item, and is categorised under Home, Furniture & DIY and Home Security, specifically under Smoke & Gas Detectors. Get your hands on this essential home security item today.