The 20-0093 PCV Catch Can Kit runs inline with the 3/8" PCV (positive crankcase ventilation) valve. Oil and sludge can enter the intake manifold through this line during normal driving. A catch can is a great way to reduce the amount of pollutants collecting in the intake manifold and degrading engine performance. Note: Because the Radium catch cans are pressure sealed, they are great for boosted applications as well, so connecting to the intake manifold is permitted.