The S300’s main advantage is portability. Its compact cylinder format and simple setup make it practical for short underwater checks such as boat cleaning, quick pool sessions, or brief shallow exploration. When filled properly, the available air supply can support several minutes of breathing, which is meaningful for tasks that do not justify full scuba equipment. As a backup air source, the form factor is easy to carry and deploy, especially when paired with an anti-lost rope for handling in water.

Breathing comfort appears improved in the upgraded S300 design, with an updated valve core intended to make inhalation smoother. A filtration approach is positioned as a cleanliness benefit, and for many users the air feels consistent enough for calm, controlled breathing. The unit also supports travel planning since it can be disassembled for transport, though air travel rules and local fill access still require preparation.

The largest operational drawback is refilling. Manual hand pumping is time-consuming and physically demanding, which can make the “portable” concept less convenient if no compressor or dive shop access is available. Runtime expectations also vary. Actual underwater duration depends heavily on breathing rate, depth, and how completely the tank is filled, so it should not be treated as a long-duration solution. Some users also report comfort issues with the mouthpiece or perceived pressure steadiness.

Overall, it fits best as a short-duration tool and safety supplement, not as a primary diving system.