Note for Use: 1, To test the collar: There is a test light (the clear plastic piece) in the package. If you want to test the collar with this light, just contact the electrodes (on the collar) and the wires (in the tester), then blow air into the sensing hole (between the tow electrodes), the light will start to light up on your 3rd time to blow, and will be brighter and brighter on your following times to blow. 2, Before using the collar, please pull out the insulating paper in the battery box to make it start to work. 3, If the collar are too sensitive to the dog's coughing or bumping, you can try to press the "-" button to decrease the sensitivity.Innoo Tech