The official Brand used in Kyokushin is ISAMI. The website is https://www.isami.co.jp Most of the gi worn by black belts that we see competing in Kyokushin tournaments wear ISAMI. They are recognizable with the blue Kyokushin kanji embroidered on the left breast and the tags on the lower lapel say "Karate Kyokushinkai" and the Kanku. The common model is K-700. ISAMI manufactures this gi without the Kyokushin marks because a lot of styles use ISAMI as well. eg Seidokaikan, Shidokan, Enshin, Ashihara... The gi is very heavy and very sweat absorbent. It is also very tough. The standard model is K-450 (same as K-700 but without the Kyokushin marks), which is the typical full-contact heavyweight gi used by most black belts of many styles. If you are looking for what in the opinion of many is the best gi on the planet, then get ISAMI K-700 and if you want you can have them embroider your style and put your style's custom tag on the bottom of the lapel. Shotokan guys like Tokaido, Goju guys like shureido. If you are a karateka who already has these and looking for a new gi, try out an ISAMI K-450. ISAMI also makes other models of different weights, all depends on what you are looking for.