Brake Fluid Tester Auto Diagnostic Brakes Oil Testing Tool Calibrated for DOT4 with 5 LED Indicator

Application Method: please install a battery before using this test pen,unplug the pen cap which is at the front end of the test pen,two metal detection probes will come out,press the power button at the top of the test pen,if there is only the green LED lights but does not twinkle,it indicates that the battery need to be replaced. After you have turnd on the power,insert the test probe into the brake fluid cup completely,the test pen will display the test result immediately through the LED light,and also maintain the test result.Then you can take out the test pen to see the test result. Indicator Instruction: Green LED ?