Ok.....so, the grates are nice and heavy duty, but they don't really work for an 18 or a modern 26er
Here is the 18" grate on the Jumbo Joe. It's just the slightest bit too big. It will sit there, but will not fall down into the lip that normally holds the grate. They will work great as elevated grates on the 22/26" grills and my 22" WSM though. For less than $5, I'm still happy
Here it is lined up against the factory grate
As far as the 26" grate. It is just a smidge too small for a modern 26er. You can get it to sit on all 4 grill tabs, but it can easily slide around and fall down into the kettle. They should work well for elevated grates. I'll probably give one to my buddy who has a vintage 26, chop one up into two elevated grates, and stash the third for a rainy day.
Here it is with the far end tight against the side of the kettle. Just a little bit short on the other end.