The water bottle fuel tank has become very popular due to the extreme light weight and increased visibility for the plumbing in the tank. This tank started out as a 500ml Figi water bottle. That works out to roughly 16.9 ounces. It comes ready to install just as the picture shows with tygon tubing for gasoline powered airplanes. The polypropylene fuel inlets are designed for 1/8 inch (3.2mm) fuel line, and they are mounted and sealed.