Shown above are 3 types of casement adjuster. The first is a rod type which is the most common. It is used for outswinging windows only and is limited by the fact that the arm may interfere with screens when used in a partially open position.
In the middle is a slide bar casement adjuster which can be used on inswinging and outswinging windows.
On the bottom is a friction type casement stay. On an outswinging window it mounts on the inside and on an inswinging window it would be mounted on the exterior.