The Series 6404 Straight Female ORB x Male NPT hydraulic adapters are crucial components designed for creating secure and leak-proof connections in hydraulic systems. The female end features an ORB (SAE Straight Thread O-ring Boss) connection, which incorporates a straight UNF thread and uses an O-ring to prevent leaks, making it ideal for medium and high-pressure applications as recommended by the National Fire Protection Association (N.F.P.A.). The female port has a machined surface and chamfer that ensures a smooth and accurate seating for the O-ring, providing a reliable seal when mated with the male NPT (National Pipe Taper) connection on the other end. NPT connections utilize tapered threads that form a metal-to-metal seal through thread deformation, which is effective for fluid and gas transfer, although they are best suited for single assembly applications and not recommended for frequent disassembly due to potential wear. The nominal pipe size for NPT connections can be determined by measuring the thread diameter and subtracting 1/4". These adapters are ideal for professionals seeking dependable hydraulic solutions that combine the benefits of both ORB and NPT connections.