What balances do I need

A quick learner from USA says:
May 29, 2014
Photos attached. Can you please tell me what balances to order? Are both sides identical or are they left and right?

WINDOW:
Andersen
Visible glass approximately 20
User submitted photos of a window balance.
Profile picture of Paul
Paul from SWISCO responded:
May 30, 2014
Check out our 24-837. This can replace Andersen balance boxes stamped with 8#31.
Andersen Sash Balance, 823, 827, 831, 837
Andersen Sash Balance, 823, 827, 831, 837
24-837
$54.20
How to replace an Andersen Window Balance
How to replace an Andersen Window Balance
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Andersen's Narroline Sash Balances
Andersen's Narroline Sash Balances
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