A 1/4 in. Female Steel Industrial Coupler is a pneumatic fitting used to connect air tools and hoses in industrial and automotive applications. It features a 1/4-inch National Pipe Thread (NPT) female connection and is constructed from durable steel, often zinc-plated for corrosion resistance. These couplers are designed to work with standard industrial-style male plugs and are commonly rated for operating pressures up to 300 PSI.