When fitted as directed it is possible to simply swing the arm of the latch (which is connected to the window) to one side which results in it disconnecting from the stationary part which is fitted to the window frame. This allows the window to be opened fully. Furthermore, this disconnection action is easiest when the arm is sticking out into the room where it would be attractive for a child to swing it around to see what happens. We have replaced them with other latches and now have the holes in our oak window frames as a lasting memory. In short - don't bother with them.