Model L is a general-purpose electro-mechanical siren that produces a distinctive sound and tonal quality for industrial applications. It has a low maximum pitch which provides excellent contrast to industrial ambient noise. Introduced in 1946, the Model L is still used today in many rugged and extreme environments and applications. The fractional horsepower motor on Model L drives a ported aluminum rotor within the specially designed stator to produce a unique sound. The recommended duty cycle is five minutes on/five minutes off.