Features: Voltage Frequency Meter AC 50-500V LED display of AC voltage and frequency simultaneously. Frequency range: AC 10.0-99.9Hz, auxiliary power: 2 wires AC50-500V. Data display is intuitive with LED two-color display (red and green), clear and easy to monitor at a glance. This Voltage Frequency Meter is easy to install with embedded mounting for added stability. The meter is designed for pure AC 50-60Hz power supply and should not be used with square wave or inverter output. Specifications: Material: Plastic Size: 70x40x25mm Measuring range: AC 50-500V, AC 10.0-99.9Hz Power supply: 2 wires AC50-500V Note: Please allow 1-3cm error due to manual measurement. Ensure you are comfortable with this before purchasing. Due to differences in monitor displays, the image may not reflect the actual color of the item. Package includes: 1 x Voltage Frequency Meter