The Best Friend electronic tick repellent with ultrasonic sound provides effective protection against ticks and fleas. The non-toxic repellent is completely environmentally friendly and safe for pets and people. The device emits ultrasonic waves that repel ticks and fleas, preventing and repelling them. The repeller is attached to the dog's collar or harness. The product is easy to use; activate the device by pressing the button for about 2 seconds (the green light will light up). You will know the device is on and working when the indicator light flashes every 9 seconds or so. To turn off the alarm, press the button for about 2 seconds. The easy-to-use electronic tick repellent is USB rechargeable and you will find both the repellent and the USB cable in the package. The repellent works for up to 20 hours on a single charge before recharging.