The 100318403 Reducing Tee Fitting has size NW25 ISO-KF flange thru ports and a reduced size NW16 ISO-KF branch port and is made of 304 stainless steel. Reducing tees are a common component of vacuum piping systems and are used to provide a reduced size 90 degree branch. Series 31 ISO-KF vacuum components are designed for use at subatmospheric pressure and use standard interface dimensions defined by the International Standards Organization (ISO) allowing them to be interchangeable with other ISO-KF compliant components. Series 31 components can be used as modular building blocks to create vacuum piping systems. IS-KF flanges are "sexless" with a symmetrical seal so that so that components are rotatable. ISO-KF vacuum flanges are joined by inserting a centering ring between the two flange faces, and securing them with a flange encompassing clamp.