The 100884012 Tee Fitting has rotatable 3 3/8 inch CF ultrahigh vacuum flanges on two ports and a nonrotatable 3 3/8 inch CF flange on the other port with standard modulus. Our tee fittings are made with 304 stainless steel and are used to create branch ports in CF flange ultrahigh vacuum (UHV) piping applications. Series 88 CF-style fittings are the standard for ultra-high vacuum (UHV) applications. They use a flat gasket placed between two knife edges to provide a vacuum tight seal. Mating flanges have identical profiles, i.e., they are sexless, eliminating the need to store two types or worry about compatibility. Series 88 CF components are suitable for use in the ultrahigh vacuum applications to below 10-13 Torr and in temperatures from -196° to 500°C. The material characteristics of the flanges, seals, screws, and nuts are selected to provide high performance throughout a wide temperature range. Rotatable and non-rotatable flanges in sizes from mini 1-1/3 to 4-5/8 inches are available with several bore sizes to fit a range of vacuum tube diameters. CF components are joined by inserting a gasket between the two flange faces, then securing the assembly with bolts. Bolts should be tightened diagonally, versus sequentially around the circumference, for a secure vacuum seal. Assembly is cost effective through reuse of components and inch dimensional stubs, sockets, and tubes. The foolproof design provides leak tight joints consistently.