I’m a freak for pens and even more so for fidget items. These pens take care of both my wants. Each pen is a big tube with each having 2 different colored liquids that fall as bubbles and blend. They are very mesmerizing and calming to watch. When you find yourself stressed, take a moment with these and let them restore peace. You can’t really tell how much ink these pens have but that can be a good thing otherwise you’d see the dark colored ink down the middle that will distract from the pretty bubbles. I’m honestly not worried about how much ink or how long these will last because long after that is gone you still have the captivating liquid bubbles to entertain yourself. These are worth every penny spent!