|Iron Armour Seal|
|Viz print media||Tekkofuin Steel Shell Seal|
|English anime||Steel Shell Seal|
|Manga||Volume #44, Naruto Chapter #408|
|Anime||Naruto Shippūden Episode #142|
|Movie||Naruto the Movie: Blood Prison|
|Game||Naruto Shippūden: Ultimate Ninja Storm 2|
|OVA||Naruto Shippūden: UNSG anime cutscenes|
|Appears in||Anime, Manga, Game, Movie|
The seal itself takes the form of the kanji for "iron" (鉄, tetsu) and is usually printed somewhere on the jinchūriki's body: Killer B's right shoulder, and Blue B's chest. Not much else is known about the seal, besides the fact that it was stated by B to be of lower-quality and weaker than the Four Symbols Seal, which was used to seal Kurama inside of Naruto Uzumaki.
- In the manga, the seal is depicted as being black. In the anime however, the seal is blue.
- In the anime, the Five Elements Unseal appears to be strong enough to break the Iron Armour Seal.