This is a compact and adjustable window holder designed to keep a window open just a few millimeters — ideal for controlled ventilation during cold winter days.

I needed a way to let in fresh air without opening the window too much and losing unnecessary heat. This design allows precise adjustment using a threaded screw and nut, so the opening can be fine-tuned millimeter by millimeter.

The holder mounts between the window frame and sash and keeps the window securely in the selected position.