Casey from SWISCO responded:
January 31, 2011
Normally the Series 770 has a stamp number that begins with the balance length.
If you are unsure of the series you selected please post some detailed photos for us to look at. If you are sure it is Series 770, please remove the window sash and place it on a scale. We need the weight of the window sash in pounds in order to determine the proper stamp option. |