I found this while cleaning my shed. It is about 20” long. On one end it has 3 hooks that pivot. The shaft is square and on one side it is marked up to 10” with marks every 1/8”. The other side is marked 25-50 each with 20 increments.
An interesting bit of trivia: This type of scale dates back to 3000BC in what is now the Middle East. They aren't super accurate, but are suitable for "close enough" weight measurements and work well even when dirty or exposed to the elements.
You hang from one hook for low weight measurements. You flip it over and hang from the other hook (that is closer to the load hanging hook) for measurements up to 50#. That feature is demonstrated in the video at the 2:25 mark if you want to see how it works.