What is the only other feature found on an air bottle besides the tank?

The gauge is a critical component of an air bottle, also known as a self-contained breathing apparatus (SCBA). It serves the vital function of providing the user with real-time information about the amount of air remaining in the tank. By monitoring the pressure gauge, firefighters can make informed decisions about how much longer they can safely operate in an environment that requires the use of breathing apparatus.

The gauge helps ensure the safety of personnel by allowing them to monitor their air supply, aiding in planning for air supply management during firefighting or rescue operations. Accurate readings from the gauge are essential for making timely exits from hazardous situations before running out of breathable air.

While other features, such as pressure release valves, nozzles, or straps, may serve specific purposes in the functionality or use of the air bottle, they do not provide the crucial air supply information that the gauge does. Thus, the gauge is recognized as the essential feature alongside the tank itself.