Stored energy of multi-wire permanent fence, maintains output voltage through heavy fence load. Indicator light flashes with every pulse. Low impedance. Features a tough outer casing with a simple plug and play installation. Ideal for controlling domesticated animals or pets around the yard. Stainless steel terminals. Covers 20 to 40 acres, or 3 to 10 miles. UL (Underwriter's Laboratories) listed. 2-year warranty.