☀DOG TRAINING & ANTI-BARK: This ultrasonic dog repeller (no need collar) helps you train your dog correct barking, sitting, aggression and other behavioral obedience, also can keep you away from dog shock and attack. ☀EASY TO USE: The device has three modes: light only, light + ultrasound for dog training and light + ultrasound for agressive dogs. First open the battery cover, then put a 9V battery (not included), only the pet can hear the sound, then turn on the switch, it works well ☀FEATURES: Rechargeable, Lightweight, Easy to carry and 20 ft range. Approximately 4.9 inches by 1.6 inches. This is portable and handheld, It is easy to put in your pocket or bags; Our dog trainer can be recharged repeatedly, good way to save more batteries. . It is effective within a range up to 20 feet. ☀FIT FOR DOMESTIC DOGS: Our device is harmless to both humans and dogs. Fit for most common small, medium, large domestic dogs. ☀NOTE: Please feel free to contact with us if you have any problem. We will provide great customer service for you.