[SPARK] Hisei Kai High-Precision Inner Barrel, Inner Diameter 6.05mm [EVOLT Exclusive, 229mm] (New for January 2026)

The ultimate inner barrel that delivers performance that satisfies SPARK custom engineers.

It is possible to dramatically improve the accuracy of Tokyo Marui's new product, EVOLT.

"Hiei®" is a high-quality, ultra-precise inner barrel made entirely in Japan, developed with the cutting-edge metalworking techniques of the craftsmen at "da Vinci," the manufacturer of the custom barrel "Guren/Raizen" series, and the SPARK concept. Further refinements have been made in various areas to create the ultimate inner barrel, "Hiei® Kai."

The base material is made from the highest quality domestically produced stainless steel produced by cold forging, and the product is carefully crafted by Japanese craftsmen using domestically produced high-precision CNC machines.

To ensure stable hop-up action, the hop-up window has been carefully shaped and polished, and the end of the barrel has an ultra-long taper of 20 mm, designed to create a layer of air that envelops the BB bullets!
The synergistic effect with the 6.05 mm tight diameter improves initial velocity, accuracy, and distance.

The inner barrel for airsoft guns, "Hiei," is a registered trademark of our company (SPARK Ltd.).

[Features of Hirei® Kai]

Super polished HOP window

• A stable hop-up is important for a stable trajectory.
• The interior walls, including the area around the HOP window, are thoroughly polished by craftsmen to eliminate any uncertainties that may affect the BB bullets.
• The HOP window is subjected to a "round cutting process" which is extremely difficult to process, which allows the HOP packing to move smoothly and maximizes its performance.

20 mm ultra-long taper

• Extremely hard cold-forged stainless steel is extremely difficult to process due to its hardness, and requires high-precision CNC machines, skilled craftsmen to select cutting teeth, and precise machining programming. The extraordinary 20 mm ultra-long taper suppresses sudden changes in resistance around the barrel exit and increases in turbulence coefficient, eliminating the negative impact on accuracy.
• This maximizes the gun's inherent accuracy.

Proudly made in Japan

• It is easy to describe the precise round cutting of the HOP window, the polishing of the inner surface of the barrel, and the long taper processing of the muzzle side, but creating an ultra-precise inner barrel using cold-forged stainless steel, which is difficult to process, requires a high level of technical skill.
• "Hirei® Kai" is a MADE IN JAPAN product that Japan is proud of around the world.