The OEM rear differential breather which comes on the Nissan C200K & M226 axles (Frontier, Xterra & Titan) is a mechanical unit that is prone to failure when dust and dirt get into the unit. When the unit fails, pressure can build inside the differential and will push out the axle seals and lead to a costly axle rebuild or replacement. This replacement breather is a non-mechanical unit that is manufactured with a durable waterproof and air-permeable membrane (similar to that found in high-performance backpacking gear!). It allows the differential to breathe with changes in temperature and atmospheric conditions.
