Birks Advertising Letterpress Engraving Plate 

This is a copper printing plate, also known as a letterpress plate or an engraving plate, used in traditional printing processes. This specific plate is an advertisement, featuring an image of silverware (likely sterling silver) and text advertising a "20% OFF" sale, for Birks, a Canadian luxury jewelry and retail company. The text on the plate is reversed, as is characteristic of printing plates, which create a readable impression when pressed onto paper. The presence of a ruler alongside the plate suggests its size and scale