1. Easy to install, simple to use, no complicated steps 2. Energy saving and environmental protection, stable performance 3. Frequency range: 20-75Hz 4. Voltage range: 60-500V AC 5. Accuracy: +/- 2% 6. Ambient temperature: 0-50 degrees Celsius 7. Opening size: 22mm 8. Overall size: about 2.8 x 5.1 x 2cm