Components of Breathing Apparatus:-
1. Cylinder:
a. Alloy Steel
b. Glass Fiber Composite
c. Carbon Fiber composite
2. Warning whistle:
3. Back Plate
or carrying Seat
With waist + shoulder harness
4.
Pressure Reducer or Control Value
5. Pressure Gauge 
6. Face Mask 
a. Head Harness
7. Lungs Demand value 