Which do you think would be easier to throw to someone who's drowning, a big ol' life preserver or a compact device about the size of a pop can? If you went with the latter – and if you spend a lot of time on the water – then you might be interested in OneUp.
Measuring 6.8 inches long (172 mm) and weighing 0.8 lb (363 g), OneUp consists of an inflatable polyurethane float with an attached CO2 canister, both of which are stuffed into a cylindrical case.
As long as everything stays dry, the float remains deflated. Upon contact with the water, though, a salt pod in OneUp dissolves. This causes a spring to be released, which in turn allows the canister to inflate the float, which pops out of the case. The whole process takes just two seconds.
Once inflated, the float can support swimmers weighing up to 330 lb (150 kg). Afterwards, the float can be deflated again, a fresh canister and salt pod can be loaded in, and the whole thing can be reused.
If you're interested in getting a OneUp, it's currently the subject of an Indiegogo campaign. A pledge of US$49 will get you a unit, when and if they reach production.
It's demonstrated in the following video
