The DS Mic headset can be used while playing online with friends. During a battle or trade, two players can speak with each other. They must have each other's friend codes registered for this to work. The advantage to using the DS Mic headset is that you can have a more private conversation (the audio comes through the one earpiece), and the Mic is closer to your mouth. It works with any game that uses voice recognition such as Pokémon Diamond Version and Pokémon Pearl Version, the Nintendogs series and Metroid Prime Hunters.