The Rat Zapper Classic Rat Trap is equipped with smart-circuit technology that senses when the rodent enters the trap. Once the rodent is inside, the rat steps onto the metal plates, completing the circuit and the trap delivers a quick, humane 8,000 volt shock. Since rats have the ability to restart their hearts, the shock is applied for 2 minutes ensuring a high kill rate. Each time the trap catches a rat, the light on top of the trap flashes red to indicate a kill.