Miniature strongboxes like this example were popular among Europe's wealthy. Because they were made of iron, yet were relatively lightweight and featured a carrying ring, they provided a safe repository for coins, documents, and jewels that could be taken on journeys. This example has the added security feature of being two-faced. One side has the true hasp, the other a false one. Prying hands had to determine which hasp actually covered the keyhole before the lock could successfully be breached.
This box is decorated with birds and foliate scrollwork in square reserves. The desired ornament was "masked off" with varnish, and acid was applied to eat away the background. The south German city of Nuremberg was known for this type of etched decoration.
"Decorative Arts Highlights from the Wendy and Emery Reves Collection," page 14