This Coast Defense Fort is a model #525 and measures 24″ x 12″ and was produced prior to 1942. It has the swivel plane launcher to the right side, the gun turrets to the front, the water and single dock to the left side and the lack of large search lights on the fort. All of these things would change in 1942. I can likely push this back further to 1940 production because it has two plane hangers instead of the one that is seen those produced in 1941. The hangers are gone in the 1942 version.
From my private collection.