These artifacts resemble tennis rackets. They may be used to intercept missiles, or even spells. If the user is very skilled, they can be hurled back at the attacker.
The rackets are more useful the rounder the missile. They are more effective against sling stones than against javelins, for example.
There are said to be two Rackets: the Royal Racket of Unwanted Return and the Lawn Racket of Unwanted Return. Some say that the first is hidden within a royal palace, and the second is hidden in the overgrown grounds of the same palace. Others say that the names derive from the fact that the Royal Racket is only useful indoors, and the Lawn Racket is only useful outdoors.