Feature: 1. It clearly displays the degree of moisture content through light-emitting diodes. High moisture content can leadto a decrease in boiling point, affecting brake performances, and can also corrode the brake master cylinder and slave cylinder, causing rust and jamming. 2. Different light color designs, red light indicates that the brake fluid needs to be replaced immediately, green light indicates fine condition, and yellow light indicates acceptable condition, but it is about to be replaced. 3. This product can be used by both car repairing stores and car owners, with simple, accurate, and quick operation. 4. Compact size for easy carrying. 5. Simple and quick measurement, safer driving. 6. l2wt-NaN Specification: The brake oil detection pen measures the moisture content of brake oil based on changes in electrical conductivity. To detect the condition of brake fluid. Features: It clearly displays the degree of moisture content through light-emitting diodes. High moisture content can leadto a decrease in boiling point, affecting brake performances, and can also corrode the brake master cylinder and slave cylinder, causing rust and jamming. Different light color designs, red light indicates that the brake fluid needs to be replaced immediately, green light indicates fine condition, and yellow light indicates acceptable condition, but it is about to be replaced. This product can be used by both car repairing stores and car owners, with simple, accurate, and quick operation. Compact size for easy carrying. Simple and quick measurement, safer driving. Specifications: Color: black Material: plastics+metal Battery: 1 * AAA battery (not included) Item size: 154 * 20 * 20mm Package size: 215 * 60 * 30mm / 8.5 * 2.4 * 1.2in Package weight: 35g / 1.2ounce Packing List: 1 * Brake Fluid Tester Package List: 1 * Brake Fluid Tester