Castle® Cleans-Rite™ Mass Air Flow Sensor Cleaner is specially formulated to safely clean components in and around the mass air flow sensor. Contaminants build up over time and must be cleaned out to ensure proper system operation. While carburetor and choke cleaners contain chemicals that can damage this system, Castle® Cleans-Rite™ will not harm oxygen sensors, catalytic converters, aluminum, or plastic parts. SAFE FOR FORD AND GM INTAKES. 20/cs