Interesting Gary, or I somehow managed to misfit mine!? Not sure how, or maybe I had a larger hover vs my smokenator.
Sold now, so no chance to find out! Shame if it does as looking to expand capacity
Here's a link right from the manufacturer that says it won't fit in the 18" kettle https://www.smokenator.com/Store/p/13/individual-hovergrill but mine does. There is not much room mind you but ABT's will work just fine. Actually there is 2 1/2" of clearance from the grill to the vent.