The GB Boy Colour (note British English spelling) is a clone of the Nintendo Game Boy Color, manufactured by a company known either as Kongfeng or Gangfeng. While it plays original Game Boy and Game Boy Color cartridges, it has a number of significant differences from the original system.
Its screen is slightly wider than that of the original Game Boy Color. More importantly, it is also backlit. This makes it much easier to see, especially in dark conditions, despite the lack of 1:1 pixel mapping.
It also often comes with a built in multicart. Not all that are available for sale have this function - where they do it is advertised either as 188 in 1 or 66 in 1. If the system is turned on without a cartridge inserted, it boots into this multicart (where present), which contains games like Contra, SPACE INVADERS, Alleyway, and occasional GB homebrew like Tic-Tac-Toe. If a cartridge is inserted, a lever inside the cartridge bay is depressed and the system loads this instead.
New units are currently available: they originate in China.