Originally Posted by tech69
there's also air ones that are convenient but you can't punch them in from the edge very far. Roper xx allows you 3" of depth from the edge. You can always drill the holes but that takes long, warps the panel slightly, and the hole has to be cleaned up of metal shavings and restraightend for optimal welding. So if you find yourself with huge panels where you'll plug weld a lot it becomes a lot of work.
This is all why I use the XX and Jr.