29" Series 390 Channel Balance

A quick learner from Jacksonville Florida says:
I was about to order 29" Series 390 Channel Balance to replace my balance 2840. How can I choose stamp option? I am attaching my part number. It has number 2840 cb and then B.S.I.

Thank you,

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Tom from SWISCO responded:
If your stamp is 2840, then that should also be the option. The S390-29 has a list of each option available, as well as how much weight each option can support. You might want to weigh your window sash just to make sure that 2840 is the right one.

I had one quick question, though. How did you decide upon the Series 390 channel balance? It's important to understand that the 2840 stamp is not a serial number of any kind, it merely lets you know what the strength of the spring is. If you chose the Series 390 based on the stamp, then you might want to double check to make sure it's correct.

Series are determined by the nylon attachments on either end of the metal channel. Carefully compare yours to those for the Series 390 to make sure they match.
A quick learner says:
Regarding your question. I came up with Series 390 based on the discussion in your forum. But I will compare this series balance with my one as you advised.
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