Cross fittings connect four pipe sections together. Crosses may have solvent weld socket ends or female threaded ends (no female threads available for PVC). They create a great deal of stress on the pipe because they have four connection points. In theory, this is the same principle that makes a 3 leg stool (a "tee") more steady than a 4 leg stool (a "cross").

If the branch line passes through the tee, the fitting becomes a Cross. If the side inlet passes through the fitting, it would be a 4-way tee. If the cross has a side inlet, it could accommodate 5 different pipes.

These cross fittings are mainly find their application in hardware industry and are made of different materials, from PVC and aluminum to any other material of choice.