B-4: One-Place Basic  Aviation Oxygen System 
Aluminum high pressure refillable cylinder, delivered empty 
113 liters/4 cu. ft. - 3.21" x 8.4" - weighs 1.6 lbs.
CGA-540 low profile valve with contents gauge and shutoff
Adjustable 12 position regulator 0 to 15 LPM, all brass interior
1 Medium concentration oxygen mask
Cylinder duration at 10,000 ft: 75 minutes w/standard mask @ 1.5 lpm