A repackaged and redesigned Commodore 64 which came out in 1987 with a slimmer case similar to the case used on the Commodore 128. A newer chip was used, the 6510, but otherwise nothing else changed. It remained fully compatible with the original Commodore 64 and Commodore 128 when using it’s C64 mode.
It was launched at a time when the Commodore Amiga and Atari St were already established and popular therefore the Commodore 64C never reached the same success of it’s predecessor.
The improved optics and keyboard does make it a more pleasant machine to use than the original Commodore 64.