This handy device uses sound waves to stop bad behavior in dogs of all sizes. With simple controls and easy-to-see lights, you can use it both inside and outside. It's built tough but is still light and comfortable to hold. Perfect for dog owners who want a peaceful home and a well-behaved pet.Upgrade your dog training tools with the R&M ENTITY Dog Trainer and experience the difference in your dog's behavior! Make training your dog easy with the R&M ENTITY Handheld Ultrasonic Dog Trainer/Bark Stopper/Dog Repeller.