Instructions for use: [1] For DC power supply: This product requires a 4-28V DC power supply. The red wire is the positive power input, and the black wire is the negative power input. A key feature of this product is its built-in reverse polarity protection circuit, which helps prevent damage due to incorrect wiring. Important: Do not connect to AC 220V. [2] Display: When the temperature sensor is disconnected, the digital display shows "- - -". The display also shows "- - -" when the temperature is below -20°C or above 100°C. [3] Temperature measurement range: -20°C to 100°C, resolution 0.1°C, accuracy ±1°C. Product Usage: (1) Measuring indoor and outdoor car temperature (2) Measuring indoor and outdoor room temperature (3) Measuring refrigerator internal and external temperature (4) Pond water temperature measurement (5) Baby bath water temperature measurement Specifications: Supply voltage: DC 4-28V Refresh rate: Approximately 1 second per update Accuracy: ±1°C Temperature measurement range: -20°C to 100°C Operating temperature range: -40°C to 80°C Display color: Red and Green Sensor type: 1M NTC waterproof metal probe Display: 0.28 inch LED Minimum resolution: 0.1°C Dimensions: 48 x 29 x 18mm (1.89 x 1.14 x 0.71 inches) Quantity: 1 set Note: Please allow 1-3mm error due to manual measurement. Ensure you are comfortable with this before purchasing. Due to differences in monitor displays, the actual color of the item may vary slightly from the images shown. Thank you. No retail packaging included. Package includes: 1 x Digital Thermometer 2 x Waterproof Metal Probes 1 x Power Supply Cable