CatStop Cat Deterrent protects your yard, garden, car or anywhere else youd rather cats not go. When cats come in range, CatStop emits a sudden, startling burst of ultrasonic sound that teaches them to stay away. Built-in motion sensor triggers a high-decibel, ultrasonic alarm that startles cats or other animals and frightens them away The sound is inaudible to humans and harmless to cats No need for chemicals, fences or barriers 9V battery required (not included)