Synchro Materials (Japanese: Ｓ（シンクロ）素（そ）材（ざい） Shinkuro Sozai, シンクロ素（そ）材（ざい） in card text before Code of the Duelist), formerly referred to as Synchro Material Monsters, are monsters used for the Synchro Summon of a Synchro Monster. When performing a Synchro Summon, all of the Synchro Materials used for that Synchro Summon are sent to the Graveyard by game mechanics before the Synchro Monster is Synchro Summoned. At least one of the Synchro Materials must be a Tuner monster.