Since I have a 2-stroke motor with not the highest gas mileage I wanted to be able to carry as much gas as possible. With the lip around the tank lockers trimmed as shown in the picture, you can fit a Tempo 12 gal tank available from West Marine. Tempo makes a 9 gal that will fit with no trimming of the lip. Notice that on the 12 gallon tank I attached a short hose for the fitting to connect to the motor. This allows the tank to be put in with the filler cap close to the outside. This makes filling the tank easier. Some like to use two six gallon tanks so that they are easier to carry if removed from the boat for filling. I like not having to switch tanks while underway as often. Hope this is a help, Joe