This test pen applies to detection of the DOT4 brake fluid performance, indicating the brake fluid condition through five LED lights, using the AC pulse testing method, greatly to reduce the polarization phenomenon during the brake fluid testing, the test result is accurate and the measuring speed is fast.
 
Interpretation of test results:
Green LED (＜1%) ON: The brake fluid performance is excellent.
Yellow LED(＜2%) ON: The brake fluid performance is fine.
Yellow LED(＜3%) ON: The brake fluid performance is OK, but it need to be detected and observed in the near future.
Red LED(＜4%) ON: The brake fluid performance is poor, it need to be replaced.
Red LED(＞4%) ON: The brake fluid performance is extremely poor, it need to be replaced immediately !