Features: 1. of temperature, humidity, airflow, dust, noise, light and dark, anti-interference, etc. About electricity: It is recommended to use a qualified DC regulated power supply, that is, a DC regulated power supply with qualified output voltage, current and ripple factor, otherwise it affect the stability of this product and may cause some abnormalities, such as: false alarm, no alarm, self- of cycle, etc. 2. The transceiver module is a field-shaped signal with a wide coverage and no blind spots. 3. Microwaves have relatively good induction effects during transmission: when used indoors, the effect is better; When used outdoors, there may be a slight decrease in sensing distance or sensitivity due to environmental factors. This is a normal phenomenon, users need not doubt it. About false positives: 1. To the eligibility of the power supply, please refer to the first item. 2. Test to that the product under test does not surround the moving object (sensing range), Weight: 0.00661386786 Pounds, Manufacturer: Ehwisbe