As with the kariginu it is worn alongside, the eboshi's exact form varies with the wearer's standing, and historically Japan had a wide vocabulary of eboshi styles distinguishing courtiers, warriors and commoners by the height, stiffness and tilt of the cap. In shrine use today the style is narrowed to the priestly forms, but the underlying principle survives, that headwear announces status before a word is spoken. The cap is fitted over hair dressed or bound in the traditional manner and secured so it holds its shape through the movements of a rite, which is part of why lacquer is used to stiffen the paper or silk rather than leaving it soft.
The Encyclopedia of Shinto describes the eboshi as one of a small set of vestment items whose form was essentially frozen once it passed into ritual use, continuing to be made in a shape secular Japanese fashion abandoned centuries ago, which is a common fate for garments that migrate from everyday wear into liturgical use across many traditions, not only this one. A priest typically keeps more than one eboshi, since the stiffened shape can be damaged by rain or rough handling, and a shrine's own equipment list commonly includes spares for use during outdoor festival processions.