1. Backlight control: Short press the key to turn on or turn off the backlight. 2. Reset Energy: Long press the key for more than 3 seconds to reset the energy. 3. Current Indication: The current has direction indication. If indicated, the current is in reverse direction; otherwise, it is in forward direction. 4. Energy Indication: Energy has direction indication. If indicated, the energy is in reverse direction; otherwise, it is in forward direction. The energy direction is determined by the current direction. If the current is positive, the energy increases, up to a maximum of 999kWh, and will hold at overflow unless reset. If the current is reverse, the energy decreases, down to a minimum of -999kWh, and will hold at overflow unless reset. 5. Working Mode: Direct power supply powered directly by test voltage. 6. Data Preservation: Energy data and backlight state are preserved when power is off. Model: 300V 50A Color: Black Material: Plastic Package Contents: 1 x Host 1 x Line 1 x Wrench Only the items listed above are included; other products are not included. Note: Lighting and different display settings may cause slight variations in the color of the item in the image compared to the actual product. Measurement error is allowed within +/- 1-3 cm.