Marseille mClassic is an external graphics processor that plugs between a game console or media player and your TV through HDMI.
It upscales lower-resolution content (like 720p or 1080p) to look sharper on modern 4K TVs.
For example, connecting a PlayStation 3 or Nintendo Switch through the mClassic makes older games look cleaner and less pixelated.
See also: Upscaling, HDMI, Graphics Processor