This is a simple piece that lifts up the headrest to an adjustment point of your choosing on the leather version of the Ikea Poang chair. I have always been a bit too tall and I developed a habit of lifting up the headrest a few inches every time I got in the chair.
The force on the headrest from leaning back, etc. still acts on the vertical wooden pieces just like before, so this only acts as a little riser and doesn't need to be particularly strong.
I have posted a left and right piece just for symmetry. You can use two lefts, or two rights.
I'd recommend first hooking the top of the clip to the chair, and then rotate the bottom on which will snap on nicely. Otherwise, you may impose too much stress on the joint if you start from the bottom and then try to push the top forward.