A more thorough explanation:

A Bill of Sight is a declaration made by an importer to a customs officer when they are unsure about the contents of a shipment. This document allows the importer to inspect the goods before paying duties.

An importer receives a shipment from overseas but is unsure about the contents. They declare a Bill of Sight to the customs officer, who allows them to inspect the goods before paying any duties.

This example illustrates how a Bill of Sight can help an importer avoid paying duties on goods that they did not intend to import.