The Mighty 55 Int'l Basketball League (M55) started started as a humbling 4-team league and expanded over the years into 3 separate divisions (D1, D2, and U20). D1 is the top-tier league, featuring players with former organized ball experience (i.e. KBL, international semi-pro leagues, NCAA college), and open to all high-level players/invited teams. D2 is limited to players with a max of university club experience/high school varsity and under, while U20 is for students 19 years and under. If you're looking to hoop in Seoul with players from around world, look no further.