This is the worlds first stacking helmet that can be stacked to store and stored. It is able to store a helmet that requires a large amount of storage space and is space-saving. The interior uses a "quick adjust headband" that can be adjusted by the interlocking mechanism of the headband and chin strap. Simply slip it on and pull the chin strap to fit your head. Can be customized using the flat structure unique to Kakumetto. You can print name name and sticker stickers in large sizes that are difficult to process with round helmets.