S&B Filter's breathers work well for axles, engines, and transmissions. These vent filters are built in the USA and available as clamp-on, push-in, or screw-in models and in black, chrome, or mixed finishes. S&B tests to the internationally accepted ISO 5011 Standard when testing for airflow, efficiency, and capacity. This is the same protocol used by most of the large automakers. We test for efficiency to make sure that your engine is protected from debris while sucking in even more air. Lastly, we monitor the capacity of the filter to see how much dirt it can hold before needing to be serviced.