Rank in Judo judo association. For a rank to be recognized, it must be registered with the national judo organization or the Kōdōkan. In Japan, the use of belt colors is related to the age of the student. Some clubs will only have black and white, others will include a brown belt for advanced kyū grades and at the elementary school level it is common to see a green belt for intermediate levels. In Europe the belt system is white, yellow, orange, green, blue, brown and black for both senior and junior practitioners. Judokas who have attained the 6th Dan may also use
Orange (colour) series, wear orange swimsuits to make them stand out. Orange astronaut suits have the highest visibility in space, or against blue sea. An aircraft's two types of "black box," or flight data recorder and cockpit voice recorder, are actually bright orange, so they can be found more easily. In some cars, connectors related to safety systems, such as the airbag, may be coloured orange. The Golden Gate Bridge at the entrance of San Francisco Bay is painted international orange to make it more visible in the fog. Next to red, it is the colour most popular for extroverts, and as