Window sash

A quick learner from Indiana says:
June 10, 2020
I have a broken window sash. On the outside is written SL 26 5 5/10/05

I found what I believe to be the correct part but when I go to choose it there are more options and I have no idea what they are for.
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Casey from SWISCO responded:
June 12, 2020

Hello,

I can't say for sure without seeing an undamaged balance but your balance resembles our S765-27 with a 26-5 spring strength option based on the stamp number you provided. If you'd like to confirm, the 26-5 option will support a sash between 17-23 lbs. Thank you!
27" Series 765 Balance
27" Series 765 Balance
S765-27
$14.16
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