Jesus guys, they're talking about portable canning systems by WELCOME TO CASK.COM
that puts beer in cans...
You know, BEER CANS?
There are threads about that one here, including someone thinking about offering a similar service for homebrewers.
NOT MASON JARS...
Mason jars are meant to hold a vaccum, not the outward pressure of carbonation pressing on the screw ring.
Drink out of them, but don't bottle in them.
They work by creating a vacuum when you can under pressure... When you put your food in the jar, seal the jar and stick it inside the boiling water bath, as it cools the vacuum draws the seal downward or inward that's why the dimple on a can is supposed to be pushed inward, and if you ever come a cross a can where it is bulging outward you are in trouble...
When you bottle, the gas builds up til it maxes out the head room (held in place by the crimped cap or the cork with wire or the gasket on a grolh bottle.....The co2 hits the barrier, maxes it and then goes back into solution/
With a mason jar you would either blow the seal and all the co2 would escape or if you were lucky enough that the seal held, more than likely the glass of the jar would explode and you would have a nice bottle grenade....
The tops for a mason jar typically is a thin metal lid with a rubberized "grommet" attached to is, really just a silicon band around the edge of the lid, and a retaining ring.
When you can, the cooling of the once heated container and it's goodies creates a vaccuum, it sucks inward.
It pulls the flat tightly Downward.
In fact many of the lids actually has a small indentation in the center of it, that when the vacuum occurs it is pulled inward on the top and leaves a little dimple. That's a sign that there is a vacuum pulling the lid down and keeping the veggies or jam sealed up nicely and protected from infection.
And usually after you remove the retaining ring, if everything is OK with the jar, you usually can feel/hear the the vaccum break, with a little *POP*
any of you who have ACTUALLY canned before, probably knows that one of the ways you can tell if your food in the can spoiled is if the little dimple is pushed outword.
In jars without the dimple it is really hard, usually the lid might feel loose or there might actually be wetness around the lid when you unscrew the retaining
the rotting food give of a gas
which expands to push up
the dimple OR it breaks the seal where the little lid gasket meets the rim of the glass.
There is considerably MORE pressure in the carbonation process of beer, often enough pressure to cause a BOTTLE BOMB, in bottles specifically made to handle the OUTWARD pressure of carbonation.
Now if you managed to find one of these older style, thick walled jars with big gaskets and flip tops...We MIGHT be having a different discussion.
But your typical jars from the grocery store...NOT.
The gas is going to break the seal and leak out...Anyone who has ever canned food and have one go bad knows it doesn't take a lot of gas from the rotting food to break the seal.
A crown bottles cap is designed to contain the Outward and upward pressure of a beer bottle, we crimp it down, we don't create a vacuum that seats it on the bottle.