3/8" Water Trap & Drain Black Aluminum For Air Ride Suspension Tank System Machined Aluminum With Built-In Drain Cock Inlet & Outlet Are Both 3/8"npt Aluminum Water Traps Having moisture in your air suspension system is the # 1 cause for corrosion in valves ,Which leads to a leaking valves .After time ,your tank can be holding more water than air The Alitair Water trap will prevent most moisture from entering you air suspension system when installed porperly