Keil für gekippte Fenster

Ein Keil, um gekippte Fenster offen zu halten.

I guess this requires a bit of explanation. This is a wedge to prop open what is simply called a window in Germany, but is apparently not that common anywhere else. German windows are of a type sometimes called tilt and turn (or tilt and swing) window. (Or German window.) They open in two ways, all the way, like a door, swinging inward, or turning around the bottom edge by something like 10°, inward again, and are held in place there by a linkage