This is a small model rocket intended to use estes "tiny" (1/2 A, 1/4 A) engines. One set of fins is different than the other set of fins, in shape and size. I have tested this rocket, and it should fly, but the nosecones requires a bit of sanding to fit. There are three types of nosecones: classic, rounded, and nearly flat. Choose whichever one best suits your taste, or experiment to see which one makes for the highest rocket launch.