Par replacement
Thanks for reaching out to us. We can supply this balance, but only as a custom order due to its configuration. Before we go any further though, I need a bit more information.
For full transparency, this exact model isn't made anymore. They stopped making it, so we can no longer sell it. The good news is that there's a modern version that works in all the same applications. The catch is that the springs are calibrated slightly differently.
With that in mind, I'm going to need you to tell me the exact weight of the sash for both windows. That's the glass panel. Any common bathroom scale will do, but we need that weight down to the ounce and as precise as you can manage.
I also need a clear photo of the hook that's at the end of the cord.
Finally, how many did you need?