I believe that the original design is from Kingii, but right now in the markets of Shenzhen gadgets, these floatation devices for swimmers are available to purchase.
When you compare the prices on Amazon, you will find that it is from 50 to 80 USD but in the market it is only 15 USD in cost.
This is very important for swimming beginners to wear it like a wristband, when you are in touble, you can just activate it and the gasbag will inflat and you will float up and be rescured by yourself.
The problem with this device is that it is almost impossible to ship the cartridge that have CO2
You can also see how it works from a Youtube video