Effective, quick and humane. New and improved design with 'Smart Circuit' technology. Power cuts when open for safety. Lights indicate activation and low battery power. Four AA batteries (not included) provide power for up to 100 kills. Requires 4 x AA batteries not included (code 84841). As a mouse travels towards the bait it crosses the metal plates which completes the circuit killing the mouse instantly. This electronic mouse killer from Procter is a unique battery-operated mouse controller. You should always read the manufacturers instructions before using this product.