A quick learner from california says:
July 5, 2016
how do i find out what weight I need? I removed old balance and it showed a 9, so I purchased the 2520, but it was not strong enough to hold up the window. is the weight on the list the weight of the window?
Tom from SWISCO responded:
July 7, 2016
Thanks for posting. Usually you want to match our options up to whatever is stamped on your balance, but if your balance has no stamp or if you're unsure what to choose, your best bet is to weigh the sash on a scale and refer to the chart on the S380-27 store page.