Identification to order parts

A home owner from San Diego says:

I came across your website via someone else who had a video on window repairs. I am looking to repair/replace my non-tilt window balance springs on four windows. They are all the same size and I have removed the balance springs and they all match. The spinrgs go in an half inch (1/2") channel and are 34 inches long. The number stamped on the side is "3390 35". Looking at your products my guess is the series 390 but I am uncertain. Hope this helps! Any question, please let me know. Thanks!!

User submitted photos of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
Hey, thanks for posting. I don't think this is the Series 390 channel balance, since the attachments have wings. I've narrowed this down to two possible channel balance Series: either our Series 380 or our Series 385.

Now, as you can see, the only difference between these two Series is their bottom shoe. The Series 380 uses the 15-005 while the Series 385 uses the 15-004. 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.
15-004 and 15-005
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