Instructions for use: [1] for DC power supply: This product requires access 4-28V for DC power supply, the red line for positive power supply, the black wire to the negative power. The greatest feature of this product: its own reverse anti-burning circuit, avoiding the user process due to improper operation problems. Friendly reminder: must not be connected with AC 220V Oh! [2] Display Description: When the temperature sensor is removed when the digital display "- - -", the temperature is below -20 or above 100 , digital also shows "- - -." [3] Acquisition normal temperature range: -20 to 100 , resolution 0.1 , accuracy of 1 . Product Usage: (1) Measuring the temperature inside and outside the car (2) Measuring the temperature inside and outside the -conditioned room (3) Measuring the temperature inside and outside the refrigerator (4) Temperature measurement pond (5) Baby bath water temperature measurement Specifications: Supply voltage: for DC 4-28V Refresh rate: about 1S / times Accuracy: 1 Measuring temperature: -20 ~ 100 Working temperature: -40 to 80 Display color: Red + Green Sensor Type: 1M NTC waterproof metal probe Display: 0.28 LED Minimum resolution: 0.1 Size: 48x29x18mm/1.89x1.14x0.71" Quantity: 1 Set Note: Please allow 1-3mm error due to manual measurement.pls make sure you do not mind before you bid Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you! No Retail Package Package Includes: 1 x Digital Thermometer 2 x Waterproof Metal Probe 1 x Power Supply Cable