Tee Fittings A tee, the most common pipe fitting, is used to combine or divide fluid flow. It is available with female thread sockets, solvent-weld sockets or opposed solvent-weld sockets and a female-threaded side outlet. Tees can connect pipes of different diameters or change the direction of a pipe run, or both. Available in a variety of materials, sizes and finishes, they may also be used to transport two-fluid mixtures.[further explanation needed]Tees may be equal or unequal in size of their three connections, with equal tees the most common.