It measures almost the same as the 15-bar section of my cut grate measures, +1/8". (I did the grate mod, cut the grate so I have a 10-bar/15-bar 2-piece grate for stowing on top of the charcoal grate). It's going to be a close fit for stowing, but the 10-bar grate section should mate up with the griddle as is, so 2/3 griddle, 1/3 grate...if I radius the corners, that is. I'm going to try a direct cook with the panel in the middle first, but these GGs get H-O-T! so I might be able to get a good sear indirect, we'll see. And grease control...gotta figure something out for that, too.