Air Knight K4 12Expand Eternal, known as Air Knight 12Expand Eternal (エアナイト・トウェルブエキスパンド・エターナル, Ea Naito Touerubu Ekisupando Etānaru) in Japan, is a Stamina Type Beyblade released as part of the Burst System as well as the Cho-Z Layer System. It was released in Japan on December 27th, 2018 for 993円 as the prize Beyblade in Random Booster Vol. 13 Air Knight.12E.Et.
Energy Layer - Air Knight K4
Main article: Energy Layer - Air Knight K4
Forge Disc - 12
Main article: Forge Disc - 12
12, like other even numbered Core Discs, is symmetrical and elliptical in shape in order to facilitate a Frame. Each side features three protrusions with the center protrusion in each set featuring molding in the shape of a "12" and four holes in the center, akin to 6. While the aggressive design of the Disc may imply high Burst potential from Disc-to-Layer contact, due to the fact that most Burst Performance Tips are of the same height, such contact is rare. Furthermore, 12's design is so aggressive that there have been numerous cases of the Disc severely damaging Layers that collide with it. Finally, 12 is the lightest Disc at the time of writing, lighter than even Armed which severely hinders Attack, Defense and Stamina potential. While the light weight would create high Burst resistance, the heavy weight of the SwitchStrike/God Layer System and the Cho-Z Layer System makes the use of lightweight Discs for Burst resistance obsolete.
Disc Frame - Expand
Main article: Disc Frame - Expand
Performance Tip - Eternal
Main article: Performance Tip - Eternal
Eternal features a sharp tip of a small diameter surrounded by a free-spinning dish made of PolyOxyMethylene (POM) thermoplastic, akin to a combination of Revolve and Bearing. The sharp tip of Eternal provides low friction with the stadium floor, resulting in high Stamina and Burst Defense properties. While the small diameter of the sharp tip may imply easy Destabilization, the wide diameter of the free-spinning ring helps maintain stability. The wide diameter of the ring also provides Eternal high precession time which is useful against Opposite-Spin and Mobile Stamina Combinations. However, due to the low friction of POM plastic, Eternal has slightly less KO resistance compared to its predecessor Revolve.
In the current metagame, Eternal is best suited for Pure Stamina Combinations due to the use of Atomic, akin to Revolve. While the POM ring may imply higher precession, akin to Bearing, the lack of a bearing mechanism means that the POM construction has a negligible effect and that precession is more dependent on how free-spinning the ring is. What does effect the precession time is the diameter of the Dish; Eternal's dish is much wider than Revolve's, making it outclass Atomic in precession time and outclass Revolve in most areas.
Eternal is slightly shorter than most other Pre-Cho-Z Performance Tips. In theory, this is meant to prevent the opponent's Layer from striking the Eternal Combination from below and Destabilizing it, thus increasing Defense potential. In practice however, due to the design of the Burst System, this increases the chances of Disc-to-Layer contact and can potentially Burst the Eternal Combination. Though the only minor reduction in height heavily mitigates the effect.
- Air Knight K4's name is based on "air", the invisible gaseous oxygen and nitrogen compound in the Earth, and "knight", a warrior who served his/her sovereign/monarch/lord as a mounted soldier in armor.
- Air Knight K4's avatar appears to be similar to Wonder Valtryek/Turbo Valtryek's avatar, but with silver armor, sports more wing attributes, and wields twin swords.
- To enforce its air motif, Air Knight K4's wings on its armor are feather-style while the six wings on its back are insect-style.