Spare Air is a miniature scuba system that is meant to provide scuba divers with a redundant gas supply in the event of an out-of-air emergency.

Spare Air is available in two different sizes: the Model 300 and Model 600, which claim to provide approximately 57 and 114 surface breaths, respectively.

How accurate are those numbers? Do they provide enough air for a diver to safely reach the surface or their dive buddy during an emergency?

Let's find out!

We brought the Spare Air 300 and 600 to Blue Grotto Dive Resort in Central Florida. To simulate the average depth of an ascending diver, we'll deploy Spare Air at 32 feet.

Then we'll time how long it takes to breathe each Spare Air down to 200 psi and count how many breaths they supply during that time.

At our dive depth of 32 feet, we expected each model to provide about half as many breaths as they're advertised to provide at the surface. We found that the 300 and 600 Spare Air models both provided just over half of their stated surface breaths when used at 32 feet, and their supply held out for four and seven minutes, respectively.

As advertised, Spare Air holds enough gas to make a real difference during an out of air emergency, giving divers enough air to safely reach the surface or their dive buddy.