By defeating a Mega Evolved boss Pokémon, the player will unlock the option to wear a Mega Ring. Once this option is available, the player can wear and take off the Mega Ring in the inventory screen. The Mega Ring will be visible on the player's left hand when it is worn.
A Mega Ring must be unlocked and worn for a player to Mega Evolve a Pokémon. If a player wears a Mega Ring, a Pokémon owned by the player will be able to Mega Evolve in battle if it is holding its corresponding Mega Stone. If the Mega Ring has not been unlocked, or if the player has unlocked the Mega Ring but is not wearing it, Mega Evolution cannot be used.