Andersen balance identification help needed

A contractor from Ridgefied, NJ says:
I found part number on existing Andersen balance (photo attached)
E59 9#27 6-78
ButI could not decide which one I should order on your product list for replacement.
Also, Is there Left side or Right hand side?
Thank you for help.

User submitted a photo of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
Please see our 24-939 Andersen sash balance. This is meant to replace balance boxes marked with "9#27."
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