I used high temp silicone grommets from Grainger. One size for the probe to slide into snugly for pit temp, and a slightly larger size for the probe to be able to reach the meat. Note the machine screw heads just above the top and bottom grommets. Those are the grate levels. The larger one in the middle is for the probes to get to the meat on either or both of grates. You can plug the holes that aren't being used with a nail.
Am I tough? Am I strong? Am I hard-core? Absolutely.
Did I whimper with pathetic delight when I sank my teeth into my first brisket? You betcha.
Chargriller Pro w/SFB 3 generic digital thermometers