This gas tank is used on the MTA2 pocket bike with a fatty exhaust. Notice the groove in the bottom/center of the tank which allows the fatty exhaust to fit without coming in contact with the gas tank.

Specifications:
Length (top of tank longest point): 8 - 8.5 inches
Length (top of tank short point): 7 inches
Half rounded channel to accommodate expansion chamber on fatty exhaust

Measurements are approximate.