Considerably less expensive than the original Coravin capsules and they seem to last for the same (still rather short) amount of time. The manufacturers state the purity of the gas is very high, so they would probably be comparable to Coravin on this count, too. To use with the Coravin system you need to remove the black adapter collars from original Coravin cartridges. I've found this quite easy, following the helpful online advice on how to do this. The secret is to free the cap with acetone/nail-polish remover. Basically you need to invert the original capsule to drip the nail polisher remover down inside the cap, then grip the neck of the cap with a good pair of pliers and twist anti-clockwise while grasping the body of the capsule in a Mole grip. The cap matches the Winaro thread, so it can then just be screwed on and it doesn't seem to need the locking adhesive which, presumably, is used in original cartridges. As far as I can see, caps can be re-used a number of times.