What component is part of the cylinder assembly in SCBA equipment?

The gauge is indeed a key component of the cylinder assembly in SCBA (Self-Contained Breathing Apparatus) equipment. The cylinder assembly primarily consists of the air cylinder itself, which stores the breathable air that firefighters rely on in hazardous environments. The gauge serves an essential function by indicating the remaining pressure within the air cylinder, allowing the user to monitor how much breathable air is still available. This is crucial for ensuring that firefighters can safely manage their air supply during operations.

In contrast, other components like the regulator control air flow to the user but are not considered part of the cylinder assembly itself; they are attached to it. Similarly, the mask is a separate piece that covers the face and provides a seal, while the harness secures the SCBA system to the firefighter but does not form part of the cylinder's structure. Each of these components has its own critical function but does not belong to the cylinder assembly in the same manner as the gauge.