The most popular thick core belts are F-700 and F-1000 (made of silk).
The Isami F-700 is our most requested thick core black belt and an all-time top selling item in our store. It has a premium finish and feels very sturdy around the waist. In fact, this is the thickest and heaviest of all our belts.
The Isami F-1000 is the most premium custom made martial arts black belt in our line. It is a thick core stiff black belt made of silk which has a unique shine and texture.