【Include】3/8"NPT Male brass Outer hex thread plug (4PCS).
【Material】High quality rust proof solid brass construction which is strong and not easily corroded, suitable for long time use.. 
【Easy Installation】Deeper and smoother threads provide effective connection, no leaking, not easy to slip. Easier and faster installation.
【Solid Brass】Brass for corrosion resistance, high temperature ductility and low magnetic permeability.
【Application】Designed to create a tighter seal. Thread plug are also great for blocking off intake manifold water ports, water pump ports, water temp and oil sender holes, engine block holes, etc.