These beauties are an exclusive for SYNH! What does this mean? It means that I had these made especially for us by design. The actual INSIDE diameter is a perfect 1″ square. The EXACT size of the Grommet width and height is 1 1/2″ to the outside perimeter. So please make sure this size will work for you! These grommets attach with 4 pre installed provided screws..1 screw is in each of the 4 corners. Sold in set of 4.