Shinobi Gauntlet

The is a  developed by Katasuke of Konohagakure's Science Ninja Weapons Team.

Overview
As its name suggests, this tool is worn on the forearm. The user initiates one of their techniques before sealing them into a scroll. The scroll is then shrunken to pill-size and is put inside the Kote. Afterwards, they can release the scroll and use the sealed technique. To use some elemental technique, the user apparently needs to form the corresponding seal first. Because using the Kote doesn't require chakra, the user can gain an advantage in battle by releasing normally chakra-taxing techniques while saving their chakra or continuing to use techniques when low on chakra, thereby keeping the user rested and less-likely to endure exhaustion; it can even be used by a non-ninja person. The wielder is also granted the ability to use techniques that would otherwise be impossible to use, such as hiden and elemental kekkei genkai techniques like Ice, Lava, and Wood Release. The Kote can affect unsealed techniques, allowing it to launch handheld techniques as a projectile.

Sealed Techniques
In Naruto Shippūden: Ultimate Ninja Storm 4, this tool gives Boruto the access to all five basic nature transformations.
 * Crimson Flame
 * Fire Release Bullet: "Blaze"
 * Lightning Release Bullet: Powerful Breath
 * Multiple Shadow Clone Technique
 * Rasengan
 * Shadow Clone Technique
 * Shadow Imitation Technique
 * Thunder Splitting Heaven and Earth
 * Water Release Bullet: Orca

Trivia

 * Masashi Kishimoto thought of a tool like this since before Naruto began. However, he could never introduce it into the manga.
 * When Konohamaru Sarutobi sealed his Rasengan into a green scroll, the kanji for appeared on the scroll. Afterwards, he also used the Wind Release hand seal when he launched the Rasengan.
 * When Boruto fought Shikadai in the Chūnin Exams, he formed the Earth Release hand seal to release the scrolls that contained the shadow clones.
 * This tool was banned in the jointly sponsored Five Great Shinobi Countries Chūnin Exams by the Seventh Hokage because it was considered an unfair advantage. Additionally, the exams were a test for nurturing young shinobi into better ones, while the Kote did the opposite.