Features: Ultrasound Function--This product is mainly used for ultrasonic dog driving equipment in outdoor environments to prevent attacks by dogs. Based on the theory that ultrasound, the dog trainer can effectively train your dogs to be obedient and stop some unwanted behaviors, such as barking, digging, chewing and more. Safe to humans & Harmless to dogs--Completely safe and does not harm dogs. No liquid propellant is used; thus being the most humane way to protect you from aggressive dogs. Note: Do not use it against the human ear. LED Flashlight Function--The blinking of the super bright LED can also make the dog clear the source and position of the sound,so as to understand that the weapon in your hand is against it. The longer you stay in this position, the greater the damage to him, and the hurry to leave. Easy To Operate--Open the battery cover and then put 1 piece 9V battery( not included), the sound is audible only to pets, finally turn on the switch and it can work well. When you encounter a dog that tries to attack you, you take out this "super-weapon"ultrasonic drive dog and launch ultrasonic waves to the dog. Dog training--Except as a pet training tool, it also can prevent you from dog attacks, fit for training many kinds of dogs, such as pets, dogs in police and shepherding, suitable for outdoor work, travel and security night patrol. So stop hesitating and make your pet obey today. Material:ABS Color:Black,Yellow Size: 1. Double head dog repeller 13.7*5.5*2.5cm 2. Single head dog repeller 13*3.8*2.3cm Note: There may be 2-3 cm error cause manual measurements .