These flywheel weights will fit any GG Pro 250/280/300cc model from "02. They change the power delivery making the bike smoother and more controlable 'off the bottom'. They will help the bike grip better and help stalling. They come with a ignition cover spacer,gasket and longer ignition cover bolts. YOU WILL NEED TO REMOVE the flywheel initially to fit the two 'top-hat' threaded parts that need to be loctited in place. Once you have fitted the weight you can take it off and refit without removing the flywheel again.