The Sistema Cambio Arma Instantaneo (カンビオ アルマ イスタンアオ, Kanbio Aruma Isutanao, lit. Instantaneous Armament Change System), or Sistema C.A.I (スイステマ シエーアイ, Sisutēma Shī Ē Ai) as it is more commonly called, is a set of 16 Box Weapons that can combine and quickly interchange between each other. The set is composed by 4 Storm-attribute Boxes, 2 Lightning-attribute Boxes, 4 Rain-attribute Boxes, 2 Sun-attribute Boxes and 4 Cloud-attribute Boxes. When going into battle, Gokudera attaches all these Boxes around his waist.