This handheld portable ultrasonic dog repeller adopts humane high-frequency ultrasound technology, emitting sound waves only sensitive to canines to stop aggressive stray dogs and correct bad habits like continuous barking without physical harm. Equipped with a built-in rechargeable lithium battery and Type-C fast charging port, it eliminates frequent battery replacement for long-term outdoor use. It features adjustable ultrasonic power gears to fit small puppies and large fierce dogs, with an effective distance up to 25 feet. Integrated bright LED flashlight serves dual purposes for night walking and auxiliary deterrence after dark. Made of sturdy lightweight ABS with an ergonomic anti-slip grip and matching carry lanyard, it slips easily into pockets or backpacks. Intelligent low-battery reminder and auto power-off extend service life, paired with overcharge protection for safe daily use. Perfect for joggers, delivery staff, dog walkers and outdoor travelers, it delivers reliable personal safety and gentle pet training in parks, streets and residential areas.