Love the Square Tempered Glass Fire Pit wind guard. It fits perfectly in our fire pit table. It arrived well packaged and was easy and quick to put together - about 20 minutes. For reference, our fire pit table is by Endless Summer and has an opening of exactly 17.5" squared. The wind guard fits inside, to the edge. The packaging indicates the exact measurements are 16.5" but that's only because the corner fasteners create a slight gap between the panels of glass - as they should for air circulation. The finished product is indeed 17.5". We look forward to enjoying a cozy warm fire on cool summer nights, and beyond! Thank you Wayfair and American Fireglass.