Channel sash replacment

A quick learner from California says:
I'm trying to determine the correct sash replacement piece to order. Can you help? I
The channel is 1/2 inch x 28 inch long. It has a marking of p A2730 on the piece.

I also have another channel that is the same configuration but has a heavier dual spring ( small spring is inside a larger one. The markings on that one is 27DS. 33.

User submitted photos of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
Hey, thanks for posting. I've narrowed this down to two possible channel balance Series: either our Series 351 or our Series 390.

Now, as you can see, the only difference between these two Series is their bottom shoe. The Series 351 uses the 15-002 while the Series 390 uses the 15-001. I can't quite tell what you have based on your pictures, though. Please carefully compare their dimensions to your own hardware and see which is a better match.
Comparison of <a href='Channel-Balance-Shoe/pd/Replacement-Sash-Support-Channel-Balance-Shoes/15-001'>15-001</a> & 15-002
The top sash guide also looks like our 18-008.

I'm afraid we don't carry double spring balances, but our balances still may work for you. Once you've decided on a Series and length, you will see a chart of strength options listed under the balance you've selected. Simply weigh your sash and compare the weight to the chart to find the best option.
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