The ink has a slightly different footprint (shape), but fits in and works fine. When I looked at the attached paperwork (yes, put a punch in my man card, I looked at the included instructions), it noted the slightly different shape. I will use them again. I purchased all three colors plus black. The yellow blocks had a slight powdery residue on them. I simply wiped them with a paper towel before inserting them, just to be safe. They cleaned up fine.