Literally, the size of a soda can, this is the smallest portable air source in the world. The “Old Faithful” of the venerable Spare Air line, this is the single-source that gives every user the safety edge. A complete SCUBA system (regulator, tank and pressure indicator) in a soda-can sized tank, the Spare Air 170 uses a balanced, single-stage regulator that screws directly onto the bottle. It stows in a custom holster that mounts to a BC, and can easily be deployed one-handed. The Spare Air 170 is always on, so it's easy to just put it in the mouth and start breathing.The 170 can be filled directly from the primary cylinder in seconds via a yoke adapter. It can also filled from a fill station or compressor with a special fitting. A built-in pressure indicator nub protrudes when the bottle is full, or the user can choose to get an optional dial pressure gauge. The bottom line: Easy to fill, stow and use, the Spare Air 170 is the perfect miniature redundant air supply system. In production since 1979, the original 1.7 cu ft 170PKYEL boasts over 100,000 units in use.