The Seachem HydroTote is a collapsible water jug that can be used to easily transport saltwater & RO water. It holds up to five gallons and when not in use you can collapse the HydroTote nearly flat when it's empty. In the picture it's shown both full and collapsed (you only get one HydroTote--the picture just shows it full and empty). The HydroTote is a great way to transport water without having to find storage space for a huge jug.