Replacement Channel Balances

A home owner from Mesa, AZ says:
I am in need of 4 replacement side load channel balances for non-tilt window sashes, also known as a block and tackle balance. for 2 vertical sliding windows. They are 9/16" which I understand you call 1/2". My 2 windows are the same size windows but on the two balances on one window, one is marked "28 4 DL Caldwell" and the other is marked "28 4 CL Caldwell". The two balances on the other window are marked "29 3 IL Caldwell".

The attached top pieces are 19-002.
The attached bottom pieces are 15-002.
So I think in need series 351.

The length of the metal bars on the one window are 28 and 15/16" not including the attached top and bottom pieces so I would think that they are 29" and model S351-29. The metal bars on the other window are 30" and I would think that the model is S351-30, even though the windows are identical. Does this seem correct to you? My concern is that the code options on you web site ( "2810, 2820, 2830, 2840, 2850 & 2860" ) do not appear on my metal channels, in fact there are no other markings on the channels. Should I order two S351-29 and two S351-30?
Profile picture of Mike
Mike from SWISCO responded:
Thanks for posting on the discussion board!

If you believe you've correctly identify your replacement balances as Series 351, here are the recommend stamp options:

29" balance with "28 4" is the S351-29 with stamp option 2840

30" balance with "29 3" is the S351-30 with stamp option 2930

Let me know if you have any questions!
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 4-7 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at 856-317-6263 or at