The Infinite Armour (無限甲蓋, Mugen Kōgai) was a unique armoured chest plate, fashioned into the shape of a tiger's face. This armour has the abilities to take almost all the damage in a fall and draw out and, at an alarming rate, absorb the chakra of anyone or anything that comes into contact with it. When Gaara's chakra-imbued sand came into contact with it, the chakra moulded into the sand was drained and the sand fell inert. When Rock Lee tried to attack Suiko directly, the armour drained the chakra out of the kick. The armour was even able to nearly absorb all of Shukaku's chakra from Gaara in a matter of moments. The chakra drained can then be used to revitalise injuries and replenish chakra. Hōki used the chakra drained by the armour to perfectly resurrect Seimei, and further empower the other weapons in his possession. Another tool, in the user's possession, can be used to extend the reach of the armour's chakra-draining ability. This becomes evident when Suiko used the armour in conjunction with a flail-like mace that served as a conduit for the Infinite Armour to drain an opponent's chakra through.
The Infinite Armour cannot drain chakra faster than a piercing projectile can penetrate the armour itself: Suiko died when Gaara felled him with a Spear of Sand, and Seimei was defeated when Gaara used his Ultimately Hard Absolute Attack: Spear of Shukaku technique to pierce the armour and then used Sand Waterfall Imperial Funeral to crush and bury both Seimei and the armour.
It is first seen worn by Suiko of the Four Celestial Symbols Men. After Suiko's defeat by Gaara, it was summoned by the Four Celestial Symbols Men leader, Hōki. While wearing the armour, Hōki summons and revives the body of the armour's creator, Seimei. He used the armour and a specialised cage to rapidly drain Shukaku's chakra from Gaara to revive Seimei and empower all of his crafted weapons. While Seimei wore it, he had all of the other weapons of the Four Celestial Symbols Men integrated onto the weapon: the Garian Sword becoming bladed-tentacles reaching from the back, the Weaknessless Soaring Shortswords becoming thin striped rings extending from around the armour, and Hōki's sword integrated to the forehead of the tiger's face by the hilt.