Unlike a simple wedge, this doorstop has a unique curved upper surface that engages both sides of the door at the same time. Once installed, it prevents the door from moving in either direction; the door cannot be jarred loose by gusts of wind or bumps by pets or children.
We even found it useful to hold the free end of a door at the correct height while installing or removing the hinge pins (which works much better than trying to use your foot).
Measuring 3" wide by 5" long, it is effective with any door gap under 1". Made in England.