Baishan Control Anti Dog Barking Outdoor Ultrasonic Safe and effective for all size and breeds of dogs.This device with battery operated. Detects barks up to 50 feet with the use of an internal microphone and 4 levels of operation including a test mode Durable and waterproof for outdoor use Designed for easy hanging or mounting on a tree,wall or fence post to keep your own dog or your neighbors dog from barking(please note this product may not work on deaf or hearing impaired dogs) Note: Keep at arm length away from the human ears to avoid hearing damage.