Sega redesigned the SG-1000 twice to try to build a system to challenge Nintendo's dominance; the SG-1000 Mark II remained compatible with the SG-1000 but failed to gain any further sales.[14][15] The next iteration, the Sega Mark III, was released in 1985, using Sega's arcade hardware for its internals to provide more refined graphics. The console was slightly more powerful than the Famicom, and Sega's marketing attempted to push on the more advanced graphics their system offered over the Famicom.[16] However, Sega found that Nintendo had also contracted other developers to only develop their games exclusive to the Famicom, and Sega was forced to develop their own titles or to port the games from the other developers themselves, limiting the size of the Mark III's library in Japan.[17] Sega attempted to follow Nintendo with a worldwide release of the Mark III, rebranded as the Master System.[18] The Master System was released in the United States in 1986, but Nintendo had similar licensing practices in the U.S. to keep developers exclusive to the NES, limiting the library of games that Sega could offer and to also ensure that another gaming crash didn't begin. Further, Sega's third-party distributor, the toy company Tonka, opted against localizing several of the Japanese games Sega had created, further capping the game library Sega could offer in the U.S. Only a total estimated two million systems were sold.[19]