A device capable of stabilizing Gates.
The Gate Key is a special device Lucca created soon after Crono and Marle first disappeared to 600 A.D. It allows the opening and closing of Gates created by the Entity, granting the party access to the various time eras of the game. It is briefly stolen by Kino, who was then pilfered by the Reptites. Azala marveled at its technological advancement, though she did not believe it had been created by human beings. It was yielded to the party after the defeat of Nizbel.
Translation: Gate Holder