Just to add a little to what Claire said about KYB's. The current (and only) listing from KYB for the X is also a hydraulic shock, similar to what she describes the ones in question to be. The KYB's are "gas filled" as she says, but not high pressure ones (like KYB used to be). Adding a low pressure gas to a shock is a means to help keep it cool. By comparison the Dr. DeCarbon design with a high pressure separate gas chamber, like Bilstein's and the old KYB's used to be, is a means of keeping the oil reservoir compressed to reduce aeration. So the difference seems to be the ones EuroSport lists do not have a low pressure gas added like the current KYB's have. While a high pressure (DeCarbon type) unit may be a better design, neither of these are that. So I'd say the overall quality of either may be more important than if they have gas added or not. But no way of knowing the answer to that.