Self-Contained Open-Circuit Compressed Air Breathing Apparatus (SCBA) with 6.8L carbon-fiber composite cylinder. Supplies clean breathing air in hazardous atmospheres (smoke, toxic gas, vapor, oxygen-deficient). Used in firefighting, chemical emergency, marine, and oil & gas industries. Meets GB 16556-2025. Five main assemblies: cylinder, pressure reducer, full facepiece, demand valve, backplate.