What length Series 770 do I have?

A handy person from Hernando FL says:
April 21, 2015
Need to replace a broken Channel Balance. Your series 770 seems to be the proper replacement. Markings on the existing balance indicate Unique Balance 27E from 2004 as shown on the attached picture. The balance actually measures 28 inches but the marking on it is 27 E. Do I order a 27 or 28 inch length?
User submitted a photo of a window balance.
Profile picture of Tom
Tom from SWISCO responded:
April 22, 2015
That's a good question. Can you confirm that the metal channel measures 28" long? Make sure you're only measuring the metal channel; don't include any clips or attachments. If it is, then I think you should go with that and choose a new stamp option more appropriate for that length.

The problem is, the 27E stamp option for the S770-27 differs from the 28E option for the S770-28. We have a chart on both store pages that show how much weight each can support. I highly recommend that you weigh your window sash to determine which of the S770-28 options would work best for your window.
27" Series 770 Balance
27" Series 770 Balance
S770-27
$12.70
28" Series 770 Balance
28" Series 770 Balance
S770-28
$12.70
How to replace a tilt-window channel balance.
How to replace a tilt-window channel balance.
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