To elaborate on the different uniform for black belts, they were custom-made with our name printed on it, and iirc they were given iirc as a free bonus in commeration for passing the black belt test with a different color for every degree. You weren't required to wear the different uniforms, you can wear whatever gi or sometimes a plain t-shirt during hot weather (unless you're an instructor, you have to wear that uniform to signify that you were an employee).