The wireless online smoke alarm can be included in the same system by a LEARN button.
When one of the detectors alarms, it emits the high frequency digital signal

(433.92MHZ), the others receive the same signal and will alarm together
to remind users to take measures. It works on the principle that infrared scatters

in the smoke to probe the smoke which is generated by the incomplete combustion
at the initial stage of the fire. It consists of photoelectric system, signal
processing identification circuit and alarm circuit. The infrared scatters on
the surface of the smoke when the smoke enters the darkroom of the detector, then

the photoelectric diode receives the scattered light and generates the photoelectric

signal current. The photoelectric signal generates the alarm signal after
being processed by the identification circuit, accordingly the purpose of alarm
is achieved. The product has a special design, modern and fashion, small
and artistic, and is of convenience to use.

Specifications:
1) Power source: one 9V battery
2) Quiescent current: 80uA  
3) Temperature: -10ºC ~ +40ºC
4) Frequency: 433.92MHZ
5) Alarm decibel: ≥85dB/3m
6) Size: (diameter) 110 x 34mm