Spare Air Scuba Divers’ Supplies Review: Features, Pros And Cons

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In this article we will review the Spare Air line of redundant air supplies for scuba divers. We will discuss how these products fit into the alternative air supply options available to divers, and we will compare the three models of Spare Air breathing devices to see what features they offer and what their advantages and disadvantages may be.

What Is Spare Air?

Spare Air is part of a whole market area of alternative breathing devices for divers. Understanding the market will help to highlight the place of Spare Air in that market and the value of their products.

Extra Air Is Always Nice to Have

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With the sophisticated gear available to modern divers, including SPGs (submergible pressure gauges ) designed to constantly monitor and alert divers regarding their air supply, does anybody really get into trouble by running low or out of air?

The answer to this is “yes”. And the implication of that answer is what you might expect—people get into trouble with their air supply, despite good training and good gear, because people are human beings. They get distracted and they make mistakes; and sometimes accidents happen as well.

In any of those situations, and especially depending upon the depth the diver is when they get into trouble, having some extra air is not only a “nice to have”, but could make the difference between life and death.

Isn’t Sharing Best?

If a diver is practicing even the most basic safety rules in their diving, they will not be diving alone. Procedure for dealing with a loss of air dictates that the first thing the diver should do is go to their buddy to share their air supply until they both can safely surface.

Again, that is certainly the correct thing to do if everything is going according to plan. However the very fact that the diver finds themselves in trouble over their air supply in the first place may indicate that things aren’t going according to plan at all.

In the event that the worst happens and a diver’s buddy is not available or for some reason cannot share air, alternatives have been developed to assist divers in this emergency situation.

Alternative Air Supply Options

Here are the three main types of alternative air supplies for divers:

  • Octopus or octo regulator
  • Alternate inflation regulator
  • Redundant air supply

Octopus or Octo Regulator

This is a secondary demand valve, or secondary regulator, that enables a diver to deliver air to a buddy diver (or to themselves) in an emergency situation. The octo-regulator uses the same air supply as the primary regulator. Usually, this system comes with an extra mouthpiece, worn at the side by the primary diver, and a long hose to enable both divers to swim comfortably while sharing air in their ascent to the surface.

Alternate Inflation Regulator

This combines the secondary demand valve with a buoyancy compensator inflation valve. Because this system offers a much shorter hose (used with the inflation valve), typically the primary diver (the one with air) will provide his buddy (the one needing air) with his primary second stage or mouthpiece, while the primary diver uses the inflation valve.

Redundant Air Supply

These systems use entirely separate cylinders (or tanks) and regulators, so they are “redundant” or “extra”  breathing systems. Typically, these extra tanks will be smaller and designed for emergency use only. The idea of the redundant air supply is not to wholly replace the main air supply, but rather to give the diver facing the emergency enough air so that they can either reach the surface or reach diving partners or buddies who can assist them.

Spare Air Is a Redundant Air Supply

This brings us back to our original question—What is Spare Air?

And the answer to that question is Spare Air is an emergency redundant air supply. Unlike other redundant systems, these products emphasize compact, unobtrusive design, offering an emergency tool that is easy for the diver to operate, maintain, and also ignore when the product is not being used—which is obviously going to be the great majority of the time.

Spare Air has been around for many years and is known for producing well-made reliable products. There has never been much of a question about whether Spare Air delivers what it claims to. When a diver needs that extra air—it’s there.

The real concern about this line of redundant air products is the amount of air it supplies to divers: an issue we will discuss in more detail below. But basically these products sacrifice size and space and weight—all good things to limit—by cutting down drastically on the amount of air that is supplied to divers. Generally that is not a good thing, although it really depends on the situation.


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Product Specs  

Spare Air offers three models of small, basic scuba tanks and regulators. Offering a simple, self-contained redundant air-supply system, all three models provide breathe-on-demand regulators (remove the protective cover from the mouthpiece and just breathe), simple operation, easy refill (through an adaptor connected to the diver’s main tank), and simple attachments that enable the Spare Airs to be carried from the diver’s buoyancy control unit or elsewhere on their gear.

Spare Airs carry between 1.7 and 3.0 cubic feet of compressed air. Surface breathes vary from 32 (for the smaller model) to 57 (for the larger sizes). The company says this should enable a diver to perform an emergency ascent from 130 feet of depth or less (with the 3.0 cubic feet cylinder) to 100 feet of depth or less (with the 1.7 cubic feet cylinder). Again, a number of variables will affect whether these estimates hold up in real-life situations.


Pricing on these products varies depending on the model. And within pricing on each model, there can be some variation as well. Generally, the Model 300 is about $270-$300. The Model 170 is about the same price as the Model 300. And the Model 300-N runs around $305.

Compared to other redundant air-supply systems, these products are moderately priced, and in some cases might even be viewed as inexpensive, especially compared to systems offering much larger tanks. As we note below, however, the Model 170 is priced about the same as the Model 300. This actually makes the Model 170 pricier in our view, because the air capacity of the Model 170 is much less than the Model 300 or Model 300-N.

How It Compares

We looked at the three models of Spare Air redundant air systems to see how they compared.  

[amazon box=”B0722NJWD1, B072596JLM, B0722NJWD1,” template=”table”]

[amazon link=”B0722NJWD1″ title=”Submersible System Spare Air ” /]

[amazon box=”B0722NJWD1″]

The Model 300 offers a small size and weight, ease of use, and maintenance, and supplies 3.0 cubic feet of air (at 3000psi) to provide a small, emergency air supply to divers.


[amazon fields=”B0722NJWD1″ value=”button”]

Maximum Capacity  

Thie Model 300 offers 3.0 cubic feet of compressed air (at 3000psi).


All three models excel are diminutive in size and weight. The model 300 weighs 2.17 pounds.

Surface Breaths

The Model 300 is said to provide up to 57 surface breaths. The number of breaths will vary depending on depth—the deeper the fewer, generally—and breath capacity of any individual diver. Again, depending on variables, this could provide up to 2 minutes of air, so roughly sufficient to complete a 100-foot ascent, though the air supply is (as the manufacturer acknowledges) extremely limited, so emergency ascents or swims should be shorter rather than longer.


  • Very compact and lightweight  
  • Very easy to use and maintain
  • Offers more air than the Model 170


  • Air supply is extremely limited
  • Cannot be used as a main tank

[amazon link=”B072596JLM” title=”Submersible System Spare Air Model 170, 300 and 300 Nitrox Package Kit 1.7-3.0 cu ft” /]

[amazon box=”B072596JLM”]

The Model 170 offers all the advantages of the Model 300, but is even more compact and lightweight than the bigger model. However to achieve this, the Model 170 also offers a smaller cylinder and air supply (1.7 meters at 3000psi). This means divers have even less air (32 surface breaths) to deal with an emergency. This definitely limits the utility of this model.


[amazon fields=”B072596JLM” value=”button”]

Maximum Capacity

This Spare Air model offers 1.7 cubic feet of compressed air (at 3000psi). While this is certainly better than nothing, it is much less emergency air and dive time than the Model 300.


The Model 170 weighs 1.5 pounds. Again, compactness and light weight are great benefits of the Spare Air breathing systems.

Surface Breaths

The Model 170 says it supplies 32 surface breaths, which the company claims will enable a diver at 100 feet to successfully complete an emergency ascent.


  • Very compact and lightweight
  • Very easy to use and maintain


  • 56% less air capacity than the Model 300
  • Ascent and swim times very limited
  • Pricey given the lower air capacity

[amazon box=”B0722NJWD1″]

The Model 300-N offers the same benefits of the Model 300, with the addition of being marked for use with nitrox air mixtures. This enables a diver breathing a nitrox mixture to switch to an emergency redundant air source that is the same as their regular air supply. In fact, the Model 300-N can be refilled directly from the diver’s regular nitrox tank.


The price for this model runs around $289.99

Maximum Capacity

The Model 300-N offers 3.0 cubic feet of compressed nitrox (at 3000psi).


This model weighs 2.17 pounds.

Surface Breaths  

The Model 300-N offers the same surface breaths, with its implications for emergency ascent and swim times from greater depths, as the Model 300.


  • Very compact and lightweight
  • Very easy to use and maintain
  • Nitrox labeled


  • Air supply is extremely limited
  • Slightly more expensive than other Spare Air models


The Spare Air redundant air supplies are made to provide divers who are running out of air with an emergency option by providing them a limited amount of additional air. This should enable a diver to make an ascent or a swim to a partner to share air supply.

The Spare Air models are all essentially the same, the chief differences being in the Model 170’s much lower air capacity. Even though this results in an even smaller, lighter backup tank than the larger Spare Airs, it seriously limits the 170’s appeal for most divers except for those taking part only in relatively shallow depth dives.

With respect to models 300 and 300-N, their scores (3.8 average) in our comparison were identical and “winning”, because they are essentially the same product, with the 300-N offering a nitrox option for divers using that air mixture. We should note that the 300-N is slightly more expensive on average than the 300.

If you are looking for a backup or redundant air supply that offers the lightest footprint or impact on your gear weight or bulk, the Spare Air models would seem to be the right choice. The only real concern, and this is especially the case with the Model 170, is the very low capacity of air available.

But the company makes the argument that these products are for emergencies and should never be relied upon as a primary air source, and so the benefits of shrinking the air capacity still enable reasonable rescue ascents—as much as from 130 feet.

Any diver who regularly dives needs a way to deal with emergencies. Overall, Spare Air products are a great choice. In some cases, they could be a lifesaver.

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