Quickly dissolves gum, varnish, fuel residues, and other deposits from carburetor, PCV valve, automatic choke, carburetor linkage, throttle body, and distributor shaft with H.E.S.T. for maximum performance and fuel economy. Improves drivability by removing deposits that cause rough idle, stalling, and loss of acceleration. Available in a variety of sizes to accommodate any job. Catalytic converter and oxygen sensor-safe.