This is the shock-free collar that uses ultrasonic sound and vibration to humanely train a dog not to bark. When a dog barks while wearing this collar, a built-in microphone detects the sound, causing the unit to emit a harmless high-pitched tone—inaudible to humans—that startles the animal into silence. It can also be operated manually for obedience training using the included 75' range remote control. The rugged nylon collar has an IPX4 water resistant rating and adjusts to fit necks 6"-24". Charges via AC adapter; remote powered by included CR 2025 battery.