Unfortunately, HP uses the 564 and 564XL label for two completely different ink cartridges. There is a Photo ink and a regular ink. Neither the store nor Amazon clarify this in the product descriptions either. As a result, I bought the wrong cartridge. I didn't realize it was the wrong cartridge until I opened it and tried to insert it in the printer. As a result, I can not return it.
The HP Photosmart printers have one large black ink cartridge and 3 or 4 smaller cartridges for color. Some models only have 3 colors and others add a 4th - photo black. So if, like me, you have the model with 3 color cartridges, you will never use a photo black cartridge. To replace the large black cartridge, order regular ink, not Photo Ink.
In case you're wondering, the difference between the 564 and 564XL is the 564XL contains more toner. Both the regular ink and the Photo Ink are available as 564 or 564XL.