A 4 joule mains energiser suitable for approx 50 acres or 15kms of fence line. The Mx4 has a 7 light performance display on the front cover. The Led bulbs light up with each pulse. The number of LED's flashing show the power of the unit (all flashing lights means 7kV. Pulsing through the fence line.Output full and half power (can be used simultaneously). To be used with 3 earth bars 1m long. An audible low output alarm indicates serious earthing problems on the electric fence line. It may also indicate a line covered with vegetation. Easy to install and maintain. 3 year warranty.