This wide black Iaido style belt is used by Iaido practitioners but is also popular among Aikido practitioners who prefer a thin and wide belt under the Hakama. This high-class model (hand-made in Japan) has a very soft cotton layer on the inside which diminishes the belt's thickness on its entire length.

This type of Obi is usually tied three times around your waist and fixed by either a knot or by simply folding the ends inside the belt.
Size calculation: 3x hips size + 50 cm (+/- 20 cm depending on how you tie the belt)

Please note that this belt can only be worn with a Hakama, tied without Hakama it will not fit properly.
This belt with exactly the same specifications also exits in black: Wide Black Belt (Iaiobi).
Because this is not a classic belt, the Aikikai logo cannot be added.

Why this type of belt in Aikido?
In basically all traditional martial arts except in Aikido, the belt tied under the Hakama is a wide belt of this type. This allows to stabilize the hips and is more comfortable for ukemi practice. Depending on the morphology, this type of belt can as well help to tie the Hakama more firmly. (Especially for practitioners having wider hips than waste.)