This Roman balance (statera among the Romans, or steelyard in Britain) is displayed near the entrance to the Exhibition. It comprises a horizontal iron beam that functions as a lever with a pivot point above which there is a hook that serves to suspend the balance.

The short arm bears a hook holding two crossed iron bars from which there hang iron chains attached to a four-legged, wooden stool with a square seat. The long arm carries a sliding, lead-filled, gourd-shaped counterweight (poise), shown at the bottom. The instrument bears a paper label inscribed with no. 1015.

This balance was used in the Santuário da Senhora das Necessidades (Sanctuary of Our Lady of Necessities), in the Municipality of Barcelos, for weighing people so that their weight could be offered in fullfillment of pledges: when faced with a difficulty or a problem, the faithful would pledge a gift to the Church of a product (e.g. wax for making candles) of the same weight as the afflicted person, in return for the favor of divine intervention to resolve the difficulty.