Zero false alarm rate, Real-time response Correct data Minimum distinguishable particle diameter:0.3 micrometer High anti-interference performance because of the patent structure of six sides shielding Optional direction of air inlet and outlet in order to adapt the different design Please note:There is a slight color difference or difference in kind, it does not affect the use, please do not mind, thank you! PIN1: VCC power supply 5V PIN2: GND power ground PIN3: NC NC PIN4: RXD:Serial port receiving pin (3 3V level) PIN5: TXD serial port sending pin (3 3V level) PIN6: RESET is suspended during use. Lowering will cause the module to malfunction. PIN7: NC NC PIN8: PWM PWM pulse width signal output pin (3 3V level) Circuit design should pay attention to 1) D9 requires 5V power supply because the fan requires 5V drive. But other data communication and control pins require 3.3V as the high level. Therefore, the main board MCU connected to it for communication should be powered by 3.3V. If the motherboard MCU is powered by 5V, the communication lines (RXD, TXD) and A level conversion chip or circuit should be added to the control line (SET, RESET). 2) The serial output only needs to be connected to PIN1, PIN2, PIN5, and other PIN pins do not need to be connected. 3) PWM output only needs to be connected to PIN1, PIN2, PIN8, and other PIN pins do not need to be connected Colour:Silver Material:Metal Package Contents: 2 x Sensor Module