This is a brass porthole in good condition and will make a really lovely bach decoration. Just be aware that on the front side, it does has some indented marks on it. Whether this is the original casting marks or someone has polished it with a grinder, we are not sure. You can still see the original stamp. All of this does add to the character of the porthole. The porthole diameter is 22cm Both brass rings are the same size, diameter inner 16.7cm and outer 21.7cm. Please note, this probably can not be used as a porthole on a boat.