·Stage-by-stage sound alarm                                            
·Sensor style and color optional.
·2/4/6/8 sensors system optional
·Anti-freezing, rainy-proof design, work well under extreme cold weather                                                               
·Working voltage: DC12V +/- 2V      
·Beeper: 70-90dB
·Working temperature: -40~+80°C
·Frequency: 40KHz
·Detection distance: 0.4-2m
·Alarm distance: 0.3-0.6m
·Best detection distance: 0.4-1.5m