In a 2x2x1 tee, what does the '1' refer to?

In the context of a 2x2x1 tee fitting, the '1' pertains to the size of the branch outlet. This number indicates the diameter of the branch that connects to the main line, which is important for understanding the flow path and capacity of the system. The dimensions of the fittings are specified in a sequence where the first two numbers represent the sizes of the main pipeline in inches, while the last number denotes the diameter of the branch outlet. Knowing this is essential for ensuring compatibility with other piping components and for maintaining proper fluid dynamics within the system.