This design is a doorstop. It can be used to keep your door fixed in any position. In particular if you have an animal that you want to let pass while keeping your door ajar this model will perfectly fit your need.
It is composed of three files: the base, the screw and the top of the screw. The later two are assembled by a M3 screw of 8 to 20 mm. I also recommend to use a chair leg pad between the feet and the ground.
This version is designed to fit to the door without any fixation and various models are available depending on the thickness of your door. If you need you can also put a pad between the door and the doorstop to adjust the fit.
You can also chose the lenght of the screw (7 or 9 cm) depending on the distance between your door and the ground.