Feature: 1. Keep Unfriendly Dogs Away: Sometime, kids or adults will be hurt by unfriendly dogs. The handheld dog repellent device can repellent dogs away. It will protect you from the unfriendly dogs to send a message to the approaching dogs before they become aggressive while you are walking, running, bicycling, etc. 2. Suitable for All Sized Dogs: Regardless of the breeds or sizes of the dogs, their hearing range is the same. ultrasound bark control aid emits ultrasonic sound at 15KHZ to 20KHZ which will not affect humans but can grab dogs' attention. This anti barking device will a safer and gentler training option. 3. Super Bright LED Flashing: The flashing of super bright LED can also make the dog clear about the source and location of the sound, thus understanding that the device in your hand is aimed at it. The longer you stay in this position, the greater the damage to him, and then walk away in a panic. 4. Ultrasound Driving: A dual head 130dB ultrasound is very stimulating for dogs' hearing, and the infrared laser enhances the driving effect of dogs at longer distances. 5. One Button Switch Start: Handheld dog trainer anti barking device is easy to operate and convenient to use. It is used for covert non lethal individual self defense. Specification: Item Type: Anti Dog Barking Device Product Material: ABS Weight: Approx. 105g / 3.7oz Frequency Range: 15-20KHZ Product Size: Approx. 13.7 x 5.8 x 3cm / 5.4 x 2.3 x 1.2in Battery : 9V Battery x 1 (shipped without battery) . Package List: 1 x Anti Dog Barking Device with Hanging Rope1 x Manual Note: When the machine is not in use, please place the gear selection switch in the "II" position. The effect of driving dogs is not significant in the following situations:1. A dog raised by oneself knows that its owner will not harm it;2. Dogs who are with their owners (dogs wield power over others). Trained large dog, (well trained).3. When the battery voltage is too low, the ultrasound energy emitted by the product will decrease.4. In dog driving mode, due to strong power output and high power consumption, do not hold down the switch for a long time. Generally, press for 3 to 5 seconds, release the switch, and then press again.5. This product emits strong ultrasonic power, please do not face people's ears when using it.