The 100319803 Bored Blank ISO-KF Flange features a size NW100 flange and a bore for 4 inch OD vacuum tubing. These bored flanges are made with 304 stainless steel and are designed for connecting various sized vacuum tubing to ISO-KF vacuum flanges. 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.