I picked up a interesting compression fitting in Italy at the weekend:

Rather than the copper/brass ring that's used in the UK, this one comes with black EPDM seals for water and yellow HNBR rings for gas. For water, it's rated -20°C to 95°C, with pressures of 16 Bar @ 30°C & 10 Bar @ 95°C. Suitable for up to 50:50 glycol:water too.

Unless you know differently, it seems to be something of an Italian spciality - it's on the Conex Italian site (and a couple of other Italian sites), but it doesn't turn up in a Web search elsewhere. There was quite a good stock in the store, so presumably they're popular. I don't have a particular use for it at the moment, but I like the concept.

Edited 21 hours ago21 hr by Mike

Interesting find. I can see the appeal, especially where you need to take a joint apart again later. With a normal olive you often end up cutting things back if it weeps, so a seal you can swap makes maintenance a lot simpler. I would still be careful to keep the water and gas versions separate and check the pipe is clean and fully seated before tightening, as that is usually where these joints let you down. Worth keeping one in the spares box to try on a low risk job first.