a key

This key is unremarkable and made of iron, with a utilitarian design and a simple, worn appearance. Its edges are slightly nicked from use, and it lacks any distinguishing marks or embellishments.

It is a key.
It weighs half a pound.

You identify a key.
It is an unsellable key.
It weighs eleven ounces, and it is worth about seventy busc.
Its keyword is key.