In England you only need a black shirt, teams are forbidden to wear black (not sure how far up that goes though) and the kit is changed every 2 years.In the US we have the flip issue--five different colors. (yellow, red, blue, green, black). Yellow is officially the primary color that all refs should have, but there is pressure past a newbie to get all five. So with long and short sleeves, that makes 10 different shirts for the fully equipped referee. (And they change the design every 5-6 years.)