Most cartridges go in countless different models of printer, so the manufacturer can never fit all of the printer models on the box.
Does the code on the box match what you've ordered?
If you've ordered Epson T0715's and the box mentions 715, or HP 364's and the box has 364 on the outside, you've got the correct items.
Does our website list your printer with that product?
Our website has no space limitations and our products list every printer a cartridge works in. Search for your product in the search bar at the top of the page (not the bar that says "I need help with..."
Once you find your product, scroll down to the printer list and check your printer is there.
Please make sure to do these checks before opening the cartridge, we can't replace or return an item once it has been opened even if it is just the outer packaging.