Balance Springs

Thanks for your photos. Based on what I see here, you have either our S380-27 or S385-27, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.

As for the stamp, yours is rated for a heavy duty load; the "DS" stands for double spring, meaning you literally have two springs (one inside the other). I'm a little confused by the marking after that, though. It looks like it was originally stenciled at 25 pounds, but someone wrote a "4" overtop of that. I'm not sure if that was a correction or what.

In these cases it's best not to guess. I suggest getting the exact weight of your sash by removing it and placing it on a scale. That will let you know for sure.

Comparison of the S380 and S385 balance shoes.

Tom is out of the office today but I agree that your stamp code would generally indicate that you have either the S380-25 or S385-25. Now, we'll need to confirm if your bottom fitting measures 1" or 1-3/32" deep as shown in Tom's last response. We'll also need to know the number of replacement balances that you need. Thank you. 

Unforutnately, the 2465 strength option will only support a window sash between 30-33 lbs. We should be able to offer replacements that will support your 38-pound sash but it would need to be a custom order. I would recommend giving our customer service team a call at (888) 991-1929 as soon as possible to see if they can cancel your order and issue you a refund before it ships.