It is a whistle marked by the tag "限定カラー" and blog articles. It allows to add a tag to a product and a blog article in this site and to display a relevant thing.
A Dolfin pro whistle has a collar released only in a specific country.
The production porpoise professional whistle of the molten to sell has color variations in various ways. That change by the year, and an attributive color is made and. While being usable for an official game, colorful and "KAWAII" to overcome! There seem to be a lot of people gathering by a hobby.