Need a replacement part help

Thanks for your patience during this busy season. We can supply this balance, but it has to be a custom order due to its configuration. before we go any further, can you please tell me the weight of the sash that the balance supports? Can you also verify the exact length of the metal channel?

If you need multiple balances, I need the same data for each balance. If any of those balances differ in terms of design, we also need photos of them to verify the right make.