Feature: 1. High Accuracy: The refreshing speed is about 300mS once, which ensures high accuracy in volt measuring. 2. Measure Range: With 0‑30V measurement range, also enables low start working voltage of 4.7V minimum. 3. Safer Working: Reverse connection protection will get you rid of burning when it's reversely connected. 4. Clear Display: Using 3 digit 0.36in LED digital tube, the clear display will show the real time voltage. 5. Easy to Install: 3 wire design largely simplifies the wiring, which can be easily completed in minutes. Specification: Item Type: Digital Voltmeter Material: PCB Function: For DIY production. Measuring Range: 0.00V-30.0V. Power Supply Range: DC 4.70-30.0V Maximum Input: DC 30.0V Allowable Error: ±1%; when greater than or equal to 10V, the error is ±0.3V; when less than 10V, the error is ±0.10V. Input Impedance:> 100K ohm. Working Current: Green, <18mA. Refresh Speed: About 300mS once. Display Mode: 3 digit 0.36in LED digital tube. Lead Length: Approx. 15cm / 5.91in Installation Hole: Hole Pitch: Approx. 28mm / 1.1in, Hole Diameter: Approx. 2.8mm / 0.11in Working Temperature: -10℃~65℃. Package List: 2 x Digital Voltmeter Note: Input voltage higher than 30V may be permanently damaged.