Shrinking keys

Shrinking keys are keys that keep shrinking until they are no longer visible. Probably intended for use as a practical joke, many wizards use them as a form of Muggle-baiting. By making a normal muggle-looking key a shrinking key, wizards can repeatedly charge for the replaced key, or simply enjoy watching the muggles become confused.

Behind the scenes

 * Shrinking keys are among the many misused muggle artifacts that Arthur Weasley came across during his time within the Misuse of Muggle Artifacts Office.