they say 26 4 then there is a "BSI" sideways and "or"

Question

I have ordered the wrong size and need to return them for the correct size. The pictures above are the old ones that need to be replaced. Can you help me choose the correct size?

User submitted photos of a window balance.

Tom · Accepted Answer

"26 4" as a stamp usually marks a 27" balance with a 2640 stamp option. You can weigh your sash and measure the length of the metal channel to confirm that. It should be 27" long with a 19 to 26 pound sash.