ARB Differential Breather KitA differential axle breather serves the important purpose on a 4WD vehicle of venting the air pressure in drivetrain assemblies such as the differential, transmission and transfer cases. Many drivetrain assemblies are fitted with a breather from the factory. These factory breathers are usually a one way valve mounted directly to the housing or remotely on a short tube. There are many short comings to this style and the ARB Differential Breather Kit is