Many cooks on this forum and other forums have used this method (I didn't come close to being that clever). It's a hollow centered lamp fitting. Normally, the lamp wire runs through it. They come in many lengths, get the shortest you can get by with IF your probes are the curved ones. I have a cap that I can screw on mine to close off the air leak.
Those pics are from two different cooks. One was "at the range" and only needed the thermo on the grill grate, the other was a cook that had one probe in the pork butt and one on the cooking grate. Hope this helps a little. Don't be in a hurry to carve up your kettle, read many of the post on our forum, there are many options. Just draping your wires over the lip works great for some ... YMMV. SJ