Most fountain pen kits we sell include both an ink cartridge and an ink pump. How do you know which one to use? It's a matter of personal preference.
The ink cartridge fits into the back of the fountain pen assembly on your pen and the ink flows from the cartridge into the nib. Once the cartridge is empty, simply replace it with a new one.
The ink pump is refillable and lets you use liquid bottle ink in your pen.