Oxygen

Oxygen is a perfect, perfectly usable product, and honestly the only one on the market. It's completely hypoallergenic, the method for breathing it in is pretty good, and you really can't do anything without it. I use it all the time with all my daily activities because I need to breathe, and since I started using it I've realized that I'm actually alive. It's pretty nice. Performance does vary by environment. The closer you are to the ocean, the better it works. At a mile up, the oxygen is thinner and lower quality, and you'll get headaches that can last a while. Staying hydrated and keeping control of your breath helps with that. An improvement would be making oxygen more accessible at every altitude. Underwater is another problem entirely. Even if you're right at the ocean, you can't get to it, which is frustrating when you're literally surrounded by the stuff. Compared to other oxygen sources, there's really no competition since it's the only one available. It's a very controlled market in that it just exists. You can buy pure oxygen, which is way better than the regular air version at around 21%, but it's also a lot stronger. You have to increase your tolerance before going all the way to 100%. It's incredibly versatile. We can make stuff fly with it, we can use it to power engines. The only real challenges are user error when people forget to breathe and accessibility issues in certain environments. How long those challenges last varies wildly, anywhere from two seconds to 48 years. Oxygen is very great, but it's also sometimes very difficult to breathe if you can't breathe it.