Size: 21X6X2CM, Weight: 0.03KG, No battery included in delivery!How to use:The brake fluid tester is based on the change in conductivity to determine the moisture change of the brake fluid. It clearly displays the water content through the light-emitting diode. High moisture content will cause the boiling point to decrease, affecting the braking performance. Red means that the brake fluid needs to be replaced immediately, green means that it is in good condition, and yellow means that it is in good condition but needs to be replaced soon.Features: Five LED indicators show the test results more accurately. Detect DOT 3, DOT4, DOT5 brake fluids, press the switch to turn on the power, the green LED is on for normal batteries, and the green light is off for batteries to be replaced (not included in delivery)! Automatic shutdown.1. Green LED light on = brake fluid water content H2O <1.5%, brake fluid qualified2. Yellow LED light on = brake fluid water content H2O = 1.5% ~ 3%, can continue to use, retest after half a year3. Red LED light on = brake fluid water content H2O > 3%, can not continue to use brake fluid needs to be replacedRed LED: replace brake fluid4. LED red light flashing: replace battery (not included in delivery)5. LED yellow light: low water content, retest after half a year6. LED green light: brake fluid pipeline / battery rowNote: delivery does not include batteries, need to bring your own !!!