A handy person from Hawaii says:
June 21, 2016
I need to replace some window balances. Looks like S385-27 is the correct choice. It is stamped 26 4 Caldwell jm but there are no other markings related to weight. Can you assist. Jim
Tom from SWISCO responded:
June 22, 2016
Thank you for posting, our "26 4" usually corresponds to our 2640 option, but you can always weigh your sash to confirm!