These adapters are KF-50 to 1 inch. NPT female pipe thread. They are commonly used to make connections between ISO-KF and 1 inch NPT-Male pipe. The ISO-KF flanges are often called quick flange fittings because they are quick to assemble. A circumferential clamp and rubber olastomer o-ring connect the flanges together. The standard sizes for quick flange fittings are KF-10, KF-16, KF-25, KF-40, and KF-50 with flange sizes NW-10, NW-16, NW-25, NW-40, and NW-50, respectively. They are made of corrosive resistant stainless steel.