Which of the following statements regarding elbows is LEAST true?

Elbows are plumbing fittings designed primarily to change the direction of flow within a piping system. While various types of elbows exist, they are not universally equipped with female threads on both ends. Often, elbows can have male threads, female threads, or be smooth depending on their application and the type of pipe they are connecting.

In contrast, elbows serve to alter the flow direction effectively, making them essential in routing piping systems — hence, this statement is true. They are also produced in numerous angles (such as 45 or 90 degrees), offering flexibility for different plumbing layouts, which is another factual assertion. Additionally, elbows come in various materials—such as PVC, copper, and steel—corresponding to differing plumbing requirements. Therefore, the assertion about them having female threads on both ends is the least accurate, as it does not encompass the full range of elbow configurations available in plumbing.