is a quick go/no-go tester relays that provides with indication of the general health and functioning of the most common Automotive relays. Tester will check for proper functioning of the relay contacts by connecting the car battery (11V--15V) to the relay coil. Tester will watch the pin configuration,the time to contacts closure and opening, consistency of the relay during each test session, Tester will light the GREEN LED if all passed during the test session,if not light the RED Connect the power leads to the car battery --black alligator clip to negative terminal, red alligator clip to positive terminal. Tester is powered up when the LED illuminates in RED. Check the relay before plugging into the tester. If it's a 4 pin relay,select"4 pin" on the tester.If it's a 5 pin relay, select"5 pin"on Plug in the relay into one of the three receptacles.Press the "TEST" button. Tester will check the pin configuration of the unknown relay. Colour:Red Material:plastic Package Contents: 1 x Voltage Tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.