Whenever plastic is used on an engine, you can almost bet you will run into some sort of failure. PPE Crankcase Breather Repair Fittings are made from machined billet aluminum and replace stock composite plastic fittings. Composite plastic can become brittle and fail. These fittings allow you to repair your stock breather system. These fittings are used with external filter/separators to eliminate engine oil contamination of your intake system.