A lot of previous reviewers have had problems with these cartridges - for example, slow delivery, suspect authenticity, suspected re-filled cartridges, out of date stock and so on. One common denominator seems to be that they have bought them from third party suppliers trading through Amazon market place. I bought mine directly from Amazon and I'm pleased I did. They were genuine HP. They were new stock with a long expiry date (December 2013). They came with lightening speed. And, at the time I bought them, they were the cheapest on line anywhere. For the record (and after a bit of research) the capacity of the different sizes of HP 364 cartridges are as follows: standard black 6ml (250 pages); standard colour 3ml (300 pages); XL black 13ml (550 pages); XL colours 6ml 750 pages). I have no reason to think this combo pack contains anything less than the standard size cartridges
