I must admit to having this particular item for over 30 years. It's the original style Porta-Pet Pocket Pen Aquarium. In viewing these pictures you'll note that something is missing... well, actually a couple of things. Most obvious is the absence of the cap that I seem to have misplaced over the past couple of years (I'm still intent on finding it!). But if you'll look closely, you'll also notice a small amount of rust around the very top. That's because they originally used to come with a small metal clip (like that found on a pen) so it could fasten securely to your shirt pocket. I lost that part as well... I really need to be more careful.