Channel balance part number

A quick learner from California says:
Please inform which part number I should use from the photos. This is for a Milgard vinyl window. Note, it appears from your website this should be a Series 380 or 385 part. The only difference being the plastic pieces on one end have a different number (but are visually indistinguishable). Since the shapes appear identical (at least to my eye). It would be nice (and save everyone some time) if guidance were given in the product descriptions(s)as to how to tell one from the other.

Regards,
Tom
User submitted photos of a window balance.
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Tom from SWISCO responded:
Hey, thanks for posting. I've narrowed this down to two possible channel balance Series: either our Series 380 or our Series 385 balances.

Now, as you can see, there is only one difference between these two Series, and that 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.
Comparison of 15-004 and 15-005
Comparison of 15-004 and 15-005
A quick learner from California says:
Thanks Tom,
I am now away and can't make that measurement until I get back home in about 10 days. As I said, it would be nice if this dimension info can be included in your site in the product description -- so I (and you) would not need to spend time going back and forth and I could have these items on order already.

Regards,
Tom

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Tom from SWISCO responded:

Hey, Tom! It's actually shown in the product image for both the S385-21 and S380-21. Check out below to see what I mean!

Close up view of the S380 balance shoe.
Close up view of the S380 balance shoe.

Close up view of the S385 balance shoe.
Close up view of the S385 balance shoe.

A quick learner from California says:
Tom,
I see now the issue. You only get these detailed dimensions when you drill down beyond the series number to the specific length. But this does not seem intuitive since length does not define the series and one wants to know whether they're in the right series before drilling down further. Better to put the info that defines the series at a higher level so the user knows they're in the right section.

Anyway, I now know what I need so am good to go. BTW, my balances are marked "20 4 FP CALDWELL" (see photo above). As I understand the terminology, the 4 stands for 4# spring force. I weighed the sliding window section and it's 20.0# (Vinyl, dual glazed, about 24x34"). Should I or could I get a stronger balance? It would make the window easier to lift.

Thanks,
Tom

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Tom from SWISCO responded:
Actually, a stamp of 20 4 usually corresponds to our 2040 option. Now, while the stamp does help determine the strength of the balance, the numbers themselves do not directly correlate to the weight of the window in pounds.

Since two balances with the 2040 option can carry a window sash weight of 15 through 23 pounds, I think this would be a good choice for your window. I would not go any stronger. Just because a spring is stronger doesn't mean that it's better. It could even make your window harder to open.
A quick learner from California says:
Thanks Tom,
A couple last questions:

1. Should I then order your 2040 series based on my photos above (you say "usually corresponds" so there may be some exceptions. We need 12 balances for 6 windows so I want to make sure I got it right).

2. These balances have failed because the internal pulley material (nylon?) has cracked. Are the replacement ones any more durable?

Tom

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Tom from SWISCO responded:
1. There are exceptions, but based on your sash weight I don't think this is one of them. The sash weight is more important than the stamp, so I would just double check that to make sure it falls under the strength rating of the 2040.

2. There really isn't any a type of pulley that's more durable than another. How long did your balances work before the pulley cracked? If they weren't that old, then I would triple check your sash weight. It's possible that the sash is heavier than 20 pounds. If they're a little older, then it was probably just that balance's time.
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