A stainless screw-in breather with a 1/8 NPT thread, threading directly into a tapped port to vent trapped pressure. Any sealed vessel that heats and cools needs somewhere for air to go, and without a breather you get pressure building on the way up and a vacuum forming as it cools, both of which push fluid past seals. Typical fitments include catch cans, differential and gearbox housings, rocker covers and fabricated tanks. Because it is small and threads straight into a 1/8 NPT port, it is easy to retrofit to an existing weld bung or drilled and tapped boss. Stainless construction stands up to under-bonnet heat and road spray without corroding.