How is the facepiece of the quick-don Scot 358 oxygen mask secured to the wearer's face?

The facepiece of the quick-don Scot 358 oxygen mask is secured to the wearer’s face using spring-loaded telescoping mounts. This design allows the mask to be quickly donned and ensures a snug fit against the face, which is critical for maintaining an effective seal that protects the user from inhaling harmful gases and provides a steady flow of oxygen under demanding conditions.

The use of spring-loaded mounts is particularly advantageous in emergency situations where time is of the essence, allowing aircrew members to don their masks swiftly and effectively while ensuring that the mask remains securely in place during high-altitude or turbulent flight conditions. This mechanism helps automate the adjustment of the mask, eliminating the need for manual tightening or securing, which may be impractical when immediate action is necessary.

The other options do not provide the same level of security or efficiency in securing the facepiece to ensure safety and efficacy during use.