What adapter is utilized to join two male hose couplings?

The adapter utilized to join two male hose couplings is a Double Female coupling. This type of coupling has two female ends, allowing it to connect to two male fittings. In fire service operations, this is essential when extending hose lines or when two hoses with male ends need to be connected to facilitate water flow.

Using a Double Female adapter ensures a secure and leak-proof connection, which is critical during firefighting operations, where maintaining water supply and pressure is vital.

The other options do not serve this purpose. A Reducer is used when connecting hoses of different diameters, a Double Male coupling would not connect two male ends directly as it lacks a corresponding female end, and a Single Coupling typically refers to a connection that involves one male and one female fitting. Thus, the Double Female is the only correct choice for this specific task.