Bark Stop, Bark Free Dog Silencer & Animal Pest Repeller - Yard Sentinel Dual Combines a Dog Silencer with Pest Repeller 2 dog silencing technologies: An ultrasonic dog silencer and a sonic dog repeller alarm 2 pest repelling technologies: high pressure ultrasonic, high-pitched siren pest & intruder alarm 2 power sources: AC Power or Batteries, weather resistant, maintenance free, no traps or chemicals, continuous activate mode, alarm dial, sensor sensitivity dial & ultrasonic dial 30 day money back if not 100% satisfied & 1 year manufacturer's warranty