My Window balance 18" length

A quick learner from Miami, FL says:
March 18, 2021
Hi,

I have attached photos of my window balance, the length of the rod is 18". most of my windows are 36x36. I think it is a series 350 but I'm not positive about the shoe. Besides etched marking it is also marked in ink as follwos: UNIQUE 17-C-30 02/17/97

Q. how many balances should I have per window, is it one or two? I only have one on one side, please let me know if that is correct. Also let me know which part to order. Thank you very much, hope to hear from you soon. You may also reach me by phone or text at 305-498-1617

Thumbnail of the uploaded file named image0.jpeg
Thumbnail of the uploaded file named image2.jpeg
Thumbnail of the uploaded file named image4.jpeg
Thumbnail of the uploaded file named image5.jpeg
Thumbnail of the uploaded file named window balance installed.jpg
Profile picture of Tom
Tom from SWISCO responded:
March 19, 2021

Hello! I agree, our S350-18 looks like a great match for your original. I can also confirm that you need two balances per sash; that would be one on each side. A window can't function properly with only one balance per sash. There are no exceptions to that rule to my knowledge.
A quick learner from Miami, FL says:
March 23, 2021
Thank you for your reply Tom, I will order it right away then.
18" Series 350 Channel Balance
18" Series 350 Channel Balance
S350-18
$9.34
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.