I know that this is a very old window opener, it has a body like espagnolette window opener except that the working principle is quite different. There are two metal bars passing by the upper and lower ends of the stadium shaped body. after inspecting, I have realized that there are 2 cylinders inside this body. When the user turns the handle, these 2 cylinders gets closer to the center making long metal bars gets closer to each other as well. This way the window opens. When thinking about it, it is a very simple mechanism yet I can't find the product because I have no idea about what term to search. That's why I am posting this question in order to replace my casement window opener accordingly. Below is the image:
