1.Backlight control: Short press the key to turn on or turn off the backlight. 2.Reset Energy: Long press the key over than 3 seconds can reset the energy. 3.Current Indication: Current has direction indication, if there is "-", it means the current is reverse direction, otherwise it is forward direction. 4.Energy Indication: Energy has direction indication, if there is "-", it means the energy is reverse direction, otherwise it is forward direction.The energy direction is judged according to the current direction, If the current is , the energy will increase, maximum is 999kwh, overflow will be maintained, unless you reset it; if the current is reverse, the energy will decrease, maximum is -999kwh, overflow will be maintained, unless you reset it 5.Working Mode: Direct power supply: Direct supply by test voltage 6.Data Preservation: Energy data and backlight state can be saved when power off. model:300v 50A Colour:black Material:plastic Package Contents: 1 * 1 * 1 * wrench Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.