JHCCoffee They have a rubber o ring. I have used them daily since the end of 2021 and not had to replace any of them although one has come slightly loose.
Comparing them to Jakes video of the Weber ones, I would say the lids are def more secure. I wouldn’t have been happy with those ones for sure.
I don’t know re airtightness - I don’t leave coffee in them for any longer than 3 days and when I do I can’t taste the difference - but so many variables involved and I drink milk drinks mainly etc..
I didn’t pay for the holders for them as I drew a line at the cost - not having these is something I regret. I’m clumsy and knock them over like they are pins in a ten pin bowling lane all the time and it drives me insane.