A wooden american style sliding window, top part fixed and bottom sliding up and down, the model is low poly and easy to animate.You can see it used in this video https://www.youtube.com/watch?v=FZjJCM7GtP0
BLEND (Blender, filesize: 1.2 MB), OBJ (OBJ, filesize: 340 KB), FBX (Autodesk FBX, filesize: 397 KB), STL (Stereolithography, filesize: 254 KB), DAE (Collada, filesize: 709 KB)