This external air filter captures airborne particulate before it enters the engine intake system. It mounts on the outside of the engine compartment and connects to the internal filter housing; the two-stage arrangement separates coarse debris in the outer element while the inner element handles fine filtration. A restricted outer filter forces the engine to draw more air through the inner element, accelerating its loading and reducing overall filtration efficiency. The manufacturer machines the sealing surfaces to match the housing's gasket groove, ensuring the filter seats without leaks. When replacing the outer element, inspect the inner filter and replace it if it shows loading.