1.Rechargeable lion battery 10 year 9 DC battery,Photoelectric sensor. 2.Red LED indicate alarm ,nice appearance. Wireless smoke detector——AF-19DescriptionWidely used for room, hall, kitchen, party, no smoking place, Hotel, Factory.Alarm mode: while smoke density reach the limited, it gives off alarm warning as well as sending wireless signal to alarm panel, High sensitivity, interconnect up to ...