Description The brake fluid tester pen measures the water content in brake fluid based on changes in electrical conductivity. It clearly indicates the water proportion via LED indicators. High water content can lower the boiling point of the brake fluid, impair braking performance, and cause corrosion or rust buildup in the master cylinder and slave cylinder, potentially leading to seizure. This product is suitable for both automotive 4S shops and individual vehicle owners, offering simple, accurate, and fast use! Specifications Style: Modern Color: Black Material: Nylon, Metal Process: Nickel-plated Assembly Required: No Product Size: 1.6*14.5cm/0.63*5.71in Package Size: 22*6*2cm/8.66*2.36*0.79in Gross Weight: 0.03kg/0.07 lbs Net Weight: 0.02kg/0.04 lbs.