These amazing, SELF FILL, steel/aluminum tanks fit inside a small, portable bag are perfect for any adventurer! Take it with you everywhere you go, it fits in your backpack and the self pump feature will keep you diving non-stop! Now there is no need to take your tank to a scuba shop for refill. While you are adventuring/hiking/traveling and come across a pool, stream, river, or any body of water YOU CAN DIVE with Portable Lungs!