This one dog diver recovered brass porthole has a 9 inch frame. The original glass is 5 1/4 inches in diameter. The opening window frame is 6 1/2 inches wide and opens and closes freely. The wing nut closure on this one dog diver recovered brass porthole works freely to lock the window closed. The flange ring on the back measures  6 inches in diameter and extends back from the main frame by 2 inches. This porthole weighs almost 7 pounds.