Features: 1.Five LED indicators show the test results more accurate. 2.Testing DOT 3, DOT4, DOT5 brake fluid. 3.Press the switch to turn on the power, the green LED light that represents the battery properly, the green light does not shine on behalf To replace the battery. 4.Automatic shutdown. 5.To check the quality of brake fluid quality. Descriptions: 1.Brake fluid detection pen is based on the change in conductivity to determine the moisture change brake fluid. 2.It shows clearly the extent of moisture contained by the light-emitting diode, high moisture content will lead to lower boiling point, affect braking performance. 3.Red indicates the brake fluid needs immediate replacement, green represents good condition, yellow indicates the state is acceptable but soon replaced. Ready for Brake Fluid Test Unscrew the brake fluid reservoir, and pull off the cap of the Brake fluid tester.Dip the test probes into the brake fluid up to the plastic rim of the device. To check Fluid Quality Press the button for power on, green LED will light up. Insert the tester into reservoir for one second then the tester result will be correctly indicated by LEDs.Repress the button for power off. The tester will automatically power off after about 15 seconds of inactivity. Technical parameters: 1. the green LED lights = water content in the brake fluid H2O 3%, can not continue to use the brake fluid needs to be replaced Red LED: change brake fluid. 4.LED red flashing: battery replacement. 5.LED yellow: low moisture content, check again in six months. 6.LED green: brake fluid lines / cell row. Green: Battery OK, that is, brake fluid does not contain water Green / yellow: brake oil in water content of less than 1%, better brake fluid performance, ease of use. Green / yellow / yellow: brake oil in water content of about 2%, brake fluid can continue to use. Green / yellow / yellow / red: brake oil in water content of about 3%, the proposed replacement of brake fluid. Green / yellow / yellow / red / red: brake oil in water content of at least 4%, the brake fluid must be replaced immediately responsible for very dangerous. Package informations: Package size:150x25x20mm/5.85x0.98x0.78in Package weight:30g/1.05oz General Box Package Package included: 1 x Brake fluid tester Noted: 1. Replace battery if the gree LED not light up any longer after you press power on button. Wash the test probe with tab water after use. 2.In case of skin contact with brake fluid, thoroughly wash the affected skin or clothing with water. 3.Do not expose brake fluid to the atmosphere for a long time as the fluid is highly hygroscopic! 4.It not included battery. Please buy at your local store .Battery model is LR03 AAA.