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:

Casement Window Opener

Working Mechanism of Casement Window Opener

  • Try an actual picture of the thing you need to replace. This appears to be a computer rendering that would not work as described, which is probably an error in computer rendering.
    – Ecnerwal
    Sep 26, 2023 at 13:38
  • @Ecnerwal I don't understand OP's explanation, but following through suggestions that it is a Cremone bolt comes up with basically the same image and with similar photographs. Sep 27, 2023 at 6:53
  • This is not an window opener, it is a lock. On casement windows, "opener" usually means a crank.
    – Z4-tier
    Sep 27, 2023 at 17:58

1 Answer 1


One productive google search term might be, “casement window cremone bolt”

  • 1
    +1, definitely a cremone bolt, I installed a few. Contrary.....
    – Jack
    Sep 26, 2023 at 14:09
  • Looks like the arm from a transom window.
    – Mazura
    Sep 27, 2023 at 1:13
  • Thank you very much! I will definitely look for it.
    – Alex
    Sep 27, 2023 at 6:45

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