Spare Air: A Detailed Comprehensive Review

A scuba diver equipped with spare air

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In this post, we take a look at Spare Air and what it and similar products can do to enhance the safety of your SCUBA adventures. The peace of mind in knowing you have Spare Air as an auxiliary supply of extra breaths beyond what is in your main tank serves to make your underwater recreational experiences more enjoyable; and more safe.

What Is Spare Air?

SCUBA diving is an awesome hobby and a fantastic pastime, but like many leisurely pursuits, there can be an element of risk associated with engaging in it. Anyone well versed in SCUBA safety can recite at least 21 or more ways you can run out of air during a dive. That is where Spare Air comes into play because it is a simple, fast, effective way to add a precious few extra breaths to your diving gear load-out.

Spare Air is a small stand-alone air supply with its own mouthpiece and regulator, independent of all your other gear: your back-up in time of need. Your Plan-B. This product gives you a chance to intercede on your own behalf and perform a self-rescue back to the surface.

The police, military, firefighters and other first responders have a saying: “Two is one and one is none.” Meaning if you have just one of a particular item, it is the same as having none, because it can be lost, experience a catastrophic malfunction, or in other ways be made inoperable or inaccessible. With some equipment this is not a big deal, but with critical hardware it can mean life or death. This is where bringing a redundant auxiliary air supply along is more than just a good idea, but a potentially lifesaving decision when you dive.

When talking safety there is but one word to describe a product like this Spare Air: indispensable. Spare Air is a lifeline between you and the surface above your dive site. It is your second chance; your guardian angel in a bottle; your security blanket.

Safety-minded boaters do not go out on the ocean without a life raft or life preserver, a parachutist does not jump without a reserve chute, a mountain climber always has a spare safety rope for his belay, and every police officer wears ballistic armor. Why? To give one a second chance against fate.

Product Specs

Spare Air for use in maritime environments comes in three different models:

Spare Air Model 300

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This model has a maximum capacity of 85 liters with a maximum pressure of 3000 PSI which equates to about 57 breaths at surface level.

Spare Air Model 170

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This model has a maximum capacity of 48 liters with a maximum pressure of 3000 PSI which equates to about 32 breaths at surface level.

Spare Air Model 300-N

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This model has a maximum capacity of 85 liters with a maximum pressure of 3000 PSI which equates to about 57 breaths at surface level. This product is for use with Nitrox dive systems.

All models of Spare Air come with a free refill adapter which allows you to fill it directly from your own scuba tanks. Also included is a safety leash to keep you from accidently losing it, especially at a critical and inopportune moment. Lastly, each Spare Air comes with a free, durable holster that will allow you to find the correct mounting solution tailored to your specific needs and style.

Remember all Spare Air models can be be filled four different ways. First the free refill adaptor lets you refill or top it off from your own SCUBA tanks. If you own a Personal Breathing Compressor, that will work too. Any local dive shop will also be able to fill it. Lastly you can fill it with a hand pump, though you will find that to be time consuming and work intensive, so we do not recommend it except in emergencies.

Mounting Spare Air to your current diving gear load-out is super simple, and you can easily attach it in whatever manner works best for you. Some popular methods are a shoulder mount and a “D” ring mount, with the bottom holster strap attached to the tank strap and the top holster strap attached to a “D” ring.

The most popular mounting method is the tank mount where the tank strap is threaded through the holster mounting strap on the back of the holster. There are all sorts of ways to mount Spare Air, so if these tried-and-true methods don’t work for you, use a little imagination to find a method suited to your needs.

What Practice Do I Need with Spare Air?

scuba divers


As with all vital and critical equipment, familiarization, planning and practice are essential to success. The manufacturer recommends that prior to your first dive with Spare Air, you attach it using your preferred mounting method using the covered holster and then practice multiple evolutions of removing the Spare Air from its holster.

After that familiarization process, they recommend you breathe the unit to empty above water, counting the number of breaths you are able to receive. Then on a normal dive you should practice actual usage of Spare Air from recreational depths so you can assess how many breaths you can draw based on depth, lung capacity weight, temperature, activity level and so forth.

How It Compares 

We picked a few similar products available on the market to see how they compare.     

  • DXDiver Pony Bottle
  • Atomic Aquatics Octopus Regulator
  • Catalina Pony Bottle Tanks

Spare Air

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Ease of Use  

Ease of use is indeed where Spare Air really shines. We really can’t emphasize this enough that Spare Air is a stand-alone piece of equipment. That means it is not reliant on any other equipment or system you are using to work correctly. Remove it from the holster, place the regulator in your mouth, hit the purge button or exhale to clear, and then start your ascent or egress. You can also hand it off to a buddy for him to use or buddy breathe using it back to the surface together.


This system may offer less capacity that some others but the availability, ease of use, and stand-alone features offset that and make it more likely you’ll actually take this along with you all the time.

Design Quality

Larry Williamson, the inventor of Spare Air, has a compelling story which drove him toward the design of this product. His own near fatal diving accident impelled him to find an answer to give divers a few extra breaths to reach safety. This is a great design by someone who knows what he’s doing.


The weight and compact size really makes this product unobtrusive, easy to travel with, easy to carry and makes it easy to find a customized place to mount it and deploy it from. A rescue breathing apparatus with this many features but such a negligible weight makes it one of the most portable safety products in its category.


  • Lightweight
  • Stand-alone
  • Easy to use
  • Multiple mounting possibilities
  • Low training curve
  • Easy to travel with


  • Less Capacity than other similar products

DXDiver Pony Bottle

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The DXDiver Pony Bottle comes in a 6 or 13 cubic foot configuration with an integrated nylon belt and holster. Some of the features include an integrated 1st Stage with 2 LP and 1 HP port with button pressure gauge, easy breathing due to conventional regulator design, and a fill adaptor tha tmakes it easy to refill.

Ease of Use

Compact and lightweight with a conventional regulator this product is simple to use but gets beat out by the competition. 



Good capacity get this particular piece of hardware a 5 star rating in this category.

Design Quality

This is an excellent quality device built to last with everything right where it should be.


At 4 to 5.7 pounds, this one is heavier and bulkier than the Spare Air. This product is more complex than a simple rescue device, but less useful than a full sized main tank. It ends up not doing very well as either!


  • Lightweight
  • Excellent capacity as a rescue device
  • Good design


  • Bulky
  • Not as easy to use as others

Atomic Aquatics Octopus Regulator

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An octopus regulator basically gives you a second access point off of your main tank. It lets you provide air to a dive buddy though it is unlikely to do you any good if you have already experienced some sort of air supply equipment failure. The upside is higher capacity assuming you have not already used it up at the moment your emergency strikes.

Ease of Use

Use of an octopus is relatively simple and quic, but may depend on other gear. Easy to use can unfortunately go to complex or impossible to use with the wrong setup.


Since it uses your main air supply, your octopus should generally or hopefully have more capacity to draw from.

Design Quality

Atomic Aquatics Octopus Regulators are high end, top of the line designs with durability and dependability built right in.


Very little in the way of weight or bulk with this 4 pound unit. Compared to the similar weight of Spare Air, though one star has been taken because it may or may not offer enough functionality during a rescue scenario.


  • Lightweight
  • Higher capacity if main air supply is not compromised


  • Not a stand-alone device

Catalina Pony Bottle Tanks

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Catalina Pony Bottle Tanks are basically smaller tanks, making them ideal for a modicum of extended capacity. Different sizes give you different options for customizing your setup.

Ease of Use

Integrating Catalina Pony tanks may give you better capacity and flexibility, but is fraught with more complexity: something you can always do without in an emergency situation.


Varying sizes of bottles allow for extra capacity and a customized approach to emergency air supplies.

Design Quality

Excellence of design and function earn these bottles a place on any serious diver’s equipment list.


A variety of sizes and capacity allows an eclectic approach to emergency air supplies and rescue strategies.


  • Variety of sizes
  • Customizable


  • Complex to use in an emergency
  • Not a stand-alone device

Conclusion… Spare Air Gets An A+

Spare Air, by any standard, deserves high marks and your serious consideration when it comes to securing your personal safety while diving. Superior safety products are driven by having a superior philosophy, and this is what sets Spare Air apart and makes it such a winner.

The two most important features of Spare Air are availability and simplicity. It’s small, it’s light, and it’s easy to find a place for and mount it to your existing equipment. That translates directly into accessibility so you have it when the need arises. All that is necessary for success is to take it out, put the mouthpiece in, purge and begin your ascent.

In real-world scenarios you may not be able to count on your dive buddy being close enough to help in an emergency. Even if he is close, he may not have enough air, you might panic, he might panic, and if you have not done a lot of buddy-breathing practice together the situation could spiral out of control, becoming a tragedy.

This is why Spare Air makes so much sense. It relies only on the performance of one person, so that in a situation where you or your buddy may be unable to react or respond, rescue is still possible. Spare Air can provide any diver a second chance, and we applaud Submersible Systems LLC, the manufacturer of Spare Air, for bringing a product like this to market.

Jack Thompson

Jack Thompson, a scuba diving enthusiast from San Diego, has spent over a decade exploring the underwater world across the globe. Sharing his passion through captivating stories and informative articles, Jack aims to inspire others to embark on their own scuba diving adventures and uncover the ocean's hidden treasures. Follow Jack on Twitter, Pinterest, Reddit, and Facebook or email him at

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