Features: 1) The online smoke alarm KD-101C can be included in the same system by a LEARN button 2) 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 3) 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 4) It consists of photoelectric system, signal processing identification circuit and alarm circuit 5) 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 6) The photoelectric signal generates the alarm signal after being processed by the identification circuit, accordingly the purpose of alarm is achieved 7) The product KD-101C has a special design, modern and fashion, small and artistic, and is of convenience to use Specifications: 1) Power source: three 1.5V batteries, one 9V battery 2) Quiescent current: 80μA 3) Temperature: -10°C ~ +40°>C 4) Frequency: 433.92MHz 5) Alarm decibel: ≥85dB/3m 6) Size: (diameter) 115 x 40mm