Spare Air is ready to step up when your SCUBA gear gives out, or when you realize 90 seconds into a snorkeling adventure that your TRITON rebreather doesn't actually, uh, rebreathe. When you're one foot too many from the water's surface and could really, really use some oxygen.
Spare Air is a completely self-contained air source. It's filled with the same oxygen compound as SCUBA tanks, but is small and light enough to holster to a belt or BC for quick access, plus requires no additional equipment to use in an out-of-air situation. Spare Air makers feel their backup system is safer and more reliable than a conventional octopus because you don't have to attach yourself to another diver to use it. As the possible attachee, you also don't have to worry that the person in need of air will panic and just grab your reg out of your mouth. Since Spare Air is a system independent of your own equipment, so too can you use it if your reg / cylinder crash (e.g., 1st stage high pressure seat leak.)
Spare Air incorporates a regulator and cylinder into one device. When you need it, just bite into the mouthpiece and breathe. The kit comes with a holster and safety leash, and a refill attachment for refilling Spare Air off any standard SCUBA yoke valve.