Operates all High Tech Pet Power Pet electronic pet doors and Sound Barrier and Yard Barrier sonic fences * Using all digital circuitry, this state of the art design provides a stronger signal and maintains better accuracy over all temperature ranges * With a fully enclosed ultrasonic speaker, the MS-4 is water-resistant and rugged * Immersible in water for short periods of time; stands up to heavy rain showers and is perfect for dogs who love to play in the snow * One size fits all dogs and cats; includes an attractive, tough 27 inch nylon strap