Window balance identification

Question

Hello
I have a window balance from a viking window it measures 26 13/16" long and 1/2 wide on the back. The photos should show the plastic attachments. The numbers 2640 are stamped on and the letters B.S.I. perpendicular to the numbers.
Charles

Jasmine · Accepted Answer

Thanks for writing in! Your channel balance assembly appears to be the Series 395 Channel Balance with a winged top guide and non-winged bottom shoe. Since yours is stamped with a 2640 , I believe you'll need the S395-27. The length from the metal channel of this balances is 27".