}The Skull Rings
are the Rings
of Hayato Gokudera
's Sistema C.A.I.
and are comprised of Lightning
, and Cloud
attribute rings. None of them were seen until Gokudera's second battle with Gamma
. He uses them to open his Sistema C.A.I Box Weapons
, which pack different Flame
-property artillery. He can then use that artillery to attack the opponent.
Lightning Tube: An electric attack that is made of Storm Flames and strengthened by Lightning Flames. Gokudera calls the combination, Flame Thunder and considers it his strongest attack.
Rain Tube: A regular Storm Flame attack with Rain Flames added. The Rain Flames' Tranquility characteristic makes it easier to break through Flame shields.
Sun Cartridge: A machine gun-like attack. The Flame Arrow uses special bullets that are infused with Storm Flames and sped up by Sun Flames.
Cloud Tube: A laser type attack that combines the Propagation of Cloud Flames and the Disintegration of Storm Flames. The attack spreads out in a tree-like diagram, making it difficult to avoid.