this is a replacement C key off an authentic Yamaha S 90 Keyboard
The C key shown in the photos is #106
Purchase may include a different number C key but will still be the exact same thing in just as good condition (All keys have been cleaned and are in very good condition).
If you are looking for another key, I currently have every key type available for the Yamaha 90 in which I could offer combined shipping and discounts for multiple keys purchased so feel free to send me a message as to what you were looking for or if you have any questions