What component allows two firefighters to share air from one cylinder without removing their facepieces?

The component that allows two firefighters to share air from one cylinder without removing their facepieces is known as the Emergency Escape Breathing Support System (EEBSS). This system is specifically designed to facilitate a safe and efficient air supply during emergencies, allowing one firefighter in distress to receive air from a partner's cylinder while both remain equipped with their facepieces.

The EEBSS includes a special connection that enables the transfer of air, ensuring immediate access to breathing support without compromising the integrity of personal protective equipment. This feature is vital in scenarios where time is of the essence and maintaining a sealed environment is crucial to prevent inhalation of hazardous atmospheres.

Other options, though they may relate to air supply or safety, serve different purposes. For example, the Completed Air Supply Line (CASL) is more about the broader context of air management in firefighting scenarios rather than a means for individual air sharing. The Rapid Intervention Crew Universal Air Coupling (RIC UAC) is designed for emergency situations where a downed firefighter can be quickly supplied with air but involves the removal of their cylinder and is not used to share air directly between two firefighters while still wearing their masks. The Pressure Relief Valve is a safety component that regulates the pressure within the cylinder but does not