8 ounce (250ml) Race Pro Small Fuel Cell for use with gasoline. They are marked 12.5 ounces, but we recommend no more than 8. This is not an IV bag. It was designed by Joe Petro and manufactured just for model use. They are twice as thick as IV bags. These feature a tapered outlet for easy air expulsion. When filling, the bag is not pressurized. Just filled and air expelled. Fuel Cells are preferred because they contain no air and can't get contaminated with water, even after prolonged submersion. They are also very compact and easy to fit almost anywhere. These top quality bags have a useful life of about 1 year. After that, they start getting hard. This bag is suitable for boats needing the minimum fuel load. Will provide about 8-10 race laps in most applications. Small Fuel Cell measures about 4-3/4 inches wide and 5.5 inches long (not including outlet).