1SAFETY MATERIAL: Handheld dog bark deterrent devices are made of premium plastic, safe and non toxic, stopping bad pet behavior, dog barking and repelling. 2RECHARGEABLE CYCLE: Ultrasonic bark control device is long lasting, cycle charging, charging method is USB connection charging, one charge can get 30 days of normal use. 3UV VIOLET LIGHT: Dog deterrent device with UV violet light, 365NM violet light beads, stray light filtering, safe and easy to use, can detect skin abnormalities such as ringworm in pets. 4MULTIFUNCTION: Ultrasonic anti barking device can also be used to detect human nose blackheads, skin diseases, pet fungus detection, cosmetic fluorescence detection, etc. 5WITH LANYARD: Dog barking control devices are equipped with a lanyard to prevent loss, easier to hold in a single hand, easy to operate. Easy to carry outside, high power, 25KHz frequency.