Duoyi DY23 Automotive Brake Fluid Tester Digital Brake Fluid Inspection Operation Manual: 1. Install one 9V(6F22) battery at the back of tester.2. After inserting the battery, press POWER button to turn on the tester, all LEDs lights turn on with buzzer sounding, which indicates the product self-test is successful.3. Press SELECT button, it will locate…