Phoenix Systems 3202-B Anti-Rust Synthetic Brake Fluid Treatment (DOT 3, 4 and 5.1 - Single Use Treats Up to 1 Liter of Brake Fluid) BrakeShot protects your brake system from corrosive brake fluid and helps to reduce costly repairs Compatible with DOT 3, 4 or 5.1. Prolongs the life of your vehicle's brake fluid and brake system Gives your vehicle brake system an instant immunization against corrosion Also comes with one brake fluid test strip to determine the level of corrosion in your brake fluid Great for classic cars that sit for months at a time