These six cartridges are suitable for the Canon inkjet printers listed below. These are the unused cartridges I still had when my printer died after many years' service.

Cartridges:
Black (photo) C551XL BK
Black (text) C550XL BK
Magenta CICCLI551 M
Cyan CLI551 CXL
Yellow (x2) CLI551 YXL

Suitable for the following printers:

Canon PIXMA iP Series: iP7200, iP7250, iP8700, iP8750
Canon PIXMA iX Series: iX6800, iX6850
Canon PIXMA MG Series: MG5400, MG5450, MG5450S, MG5500, MG5550, MG5600, MG5650, MG5655, MG6300, MG6340, MG6350, MG6400, MG6450, MG6600, MG6650, MG7100, MG7150, MG7500, MG7550
Canon PIXMA MX Series: MX720, MX725, MX920, MX925 [1]

Unused Compatible Printer Ink Cartridges - still sealed (Market Deeping PE6)