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 1.5 liter Figi water bottle. That works out to roughly 50.7 ounces. It comes ready to install just as the picture shows with tygon tubing for gasoline powered airplanes. Fuel inlet is 4mm brass for 1/8 inch ID fuel line. Vent line is polypropylene and designed for 3/16 inch (3.2mm) fuel line, and they are mounted and sealed.