(Note that you can get the whole 10 windows collection, free sample included, at a great price at https://www.cgtrader.com/3d-models/architectural/window/simple-windows-collection)

This is a free sample from my simple windows collection. This one in particular was the last one of the set, so I was kinda in a hurry so geometry is far from optimal (as you'll be able to tell by the detail views), since it was made mostly cutting apart and pasting together parts from the already made windows. Therefore, polygon count is pretty high on this one, considering the simple general design. Nonetheless, I hope you can take a free look at this one mostly to check that it, and therefore any other window in this collection, works fine for you in terms of file compatibility, general construction and details and those sorts of things.

A simple and small square window I made as part of a ten windows set I had to create for a project (all available here on CGtrader, sold separately or as a pack). The idea was to have a full set of windows in several forms, all simple but nice looking even in a close-up, without having a very defined style in themselves, so they would fit with as many architectural styles and interior decorations as possible without looking out of place in any of them.

All formats are divided in three basic parts:An outer frame, done as a single CLOSED polysurface, so it can be easily used to boolean or subtract from the wall you mean to place the window in without problems.An Inner frame, done as a single OPEN polysurface, which I hope you'll find perfectly finished to look nice but still very simply done.Glass pieces, which should match perfectly with the inner frame.

I'm also including all the profiles used, in rhinoceros format (3dm), so you can easily make any modifications or create and entire new shape with the same style, if you were to have to need for that.

Native format is Rhinoceros' 3dm and exported to other formats (obj, fbx, 3ds). All version are very close to 12k polys. Model was uploaded as shown on the viewport captures (with no textures or materials). Rendered image was made just for showing with very basic materials and AGS glass. If any particular format, format configuration, or anything else is required, just let me know.