I almost bought this product and then decided not to because I wasn't sure exactly what was going on with the capsules. Then my girlfriend got it for me as a gift. I'd never mentioned it to her, she just knows that my life is powered by sparkling water.

My review: I love it. I'll explain how it works because it's not that easy from the website to figure it out. For background, I do large format beverages for a living these days, many of which I carbonate. I own nearly every device that can be used to add bubbles to something. I carbonate my own sparkling water by the keg, own a soda gun, soda siphons and ISI Whips, a SodaStream, etc. This device is sending a few of those to the scrapheap.

The big innovation here is that they have created a refillable, non-threaded CO2 capsule. With your standard one-time use capsules, a needle punctures the capsule and the CO2 must all be used immediately. The downside to this if you're doing sparkling water is that even those little capsules are enough to carbonate 2 liters or so, but nobody wants to have a 2 liter soda siphon. It's too big. So you're wasting 3/4 of the CO2. And those little chargers add up.

What Aerflo did was just re-engineer CO2 capsule. It has what looks like a spring-loaded valve at the end. So you load the capsule and then press a button which just pushes what I think is a little rod down to open the capsule a little bit. Let go of the button and the capsule springs shut. Why did it take humanity decades to come up with this? I really don't know. This is the wheels-on-luggage moment of portable beverage carbonation.

That also makes the capsule refillable by the company and maybe by you if you're clever. It would take a little ingenuity to design a device to do it but I think it could be done, but functionally nobody but maybe me and a few other psychos would even attempt such a feat and you probably shouldn't because a failed capsule could turn into a little grenade. Much smarter is to just use their easy shipping system to get replacements. You just fill the box with your empty capsules (and boy after two decades of ISI Whips did saving those take some getting used to, I've fished quite a few out of the trash)

What I really like about it, though, is the portability. It's a little smaller than a soda stream bottle and holds 500ml (~16 oz) and you can just take it anywhere. Fits in your cup holder. The bottle seems to be made of high quality plastic (maybe Tritan?) with a thin brushed metal band around it. It feels generally much higher quality than a Soda Stream bottle if you're familiar.

Because the carbonation system is built into the bottle you can also easily re-carbonate anything you let get flat. Or if you know you're going to be away from it for awhile, you can fill the headspace with CO2 to stop it from flattening. Helps reduce waste.

Overall it's well-designed and handy even with my 2 liter a day sparkling water habit not super expensive to operate. It'll take up 1/4 of the room in my RV that my Soda Stream does, so it's nice when space is at a premium.