A diff breather kit stops your differentials (as well as gearbox and transfer case) from sucking in water when driving through river crossings and large water hazards, leading to serious and expensive repairs.
To overcome this, it is recommended to install a breather kit which acts similar to a snorkel for your differentials, gearbox and transfer case. The breather kit is primarily a hub which transfers air in and out of the critical vehicle components; the kit includes a length of air tubing which is run to a high point (usually under the vehicle’s bonnet) where it is most protected from dust and water ingress when drawing air back in.
Out of the box, the 4 port ARB Diff Breather Kit can be connected to all four key components (front diff, rear diff, transfer case and gearbox) and comes with enough tubing and fixtures to connect to the most common application of two differentials. With a small amount of additional tubing and fixtures (sold separately), the one kit will also accommodate your transfer case and gearbox.