When our Canon multipurpose machine was about ten months old it stopped printing properly, and the engineer who came to repair it told us it was clogged from our use of compatible cartridges; he said Canon inks have special solvents in them. We had thus broken the terms of the guarantee, but he was very nice about it and let us off with a caution to use only genuine Canon cartridges, which we have since adhered to, even though compatible ones are much cheaper, and we have had no further problems. Every time we need new cartridges, I always search the net for the best price I can find, and in this instance Amazon, with no p&p on this item, was the lowest. The item was boxed, too, not just a film-covered one out of a multi pack like some sellers send.