The Master System Player from RetroSix is a brand new device made in tribute to the original Master Gear Converter — a simple adaptor that slots into the Game Gear's cartridge port and allows western-style Master System cartridges to be played directly on the console.

Similar in concept to the Power Base Converter for the Mega Drive, this works because the Game Gear is essentially an upgraded Master System under the hood. The hardware has no trouble running Master System games, though it cannot provide additional features such as FM Sound from the FM Sound Unit. Native Sega Card support is not included, though could theoretically be achieved in combination with a Card Catcher and a Master System Region Converter.