Up/Down Window Channel Balance

A home owner says:
Aluminimum frame, spring, nylon thread control mechanism. I browsed your site for the the part, but could not find it. Attaching couple of images related to the part for you to help me buy the part.

Thanks
Sanjeev
User submitted photos of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
Based on these pictures, I believe you have either our S380-27 or S385-27, depending on the size of your shoe. The shoe size is the only difference between these two balances, so you will need to measure yours to confirm.
A home owner says:
After I measured the shoe size, it looks like S385-27 is the right part for me. But, how do I pick the sash weight option ? Attaching a picture of my window for you to suggest the appropriate sash weight option I need to pick.

Thanks
Sanjeev
User submitted a photo of window hardware.
Profile picture of Tom
Tom from SWISCO responded:
I'm afraid seeing the window doesn't tell us what option you need. Your stamp does, though. Since you have "26 4" stamped on your balance, our 2640 option should be what you need. If you want to be 100% sure, you can always weigh your sash on a scale and refer to the chart we have on the S385-27 store page.
How to Replace a Non-Tilt Channel Balance
How to Replace a Non-Tilt Channel Balance
VIDEO
WATCH >
How to Repair a Jammed Window
How to Repair a Jammed Window
VIDEO
WATCH >
How to Identify Replacement Channel Balances
How to Identify Replacement Channel Balances
VIDEO
WATCH >
How to replace a non-tilt channel balance
How to replace a non-tilt channel balance
GUIDE
READ >
Choosing a Non-tilt Channel Balance: What Will We Need?
Choosing a Non-tilt Channel Balance: What Will We Need?
GUIDE
READ >
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 3-4 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at (888) 991-1929 or at help@swisco.com.