This flywheel weight will fit any GG Pro 250/280/300cc model with an Idria ignition. The flywheel weight will change the power delivery making the bike smoother and more controllable off the bottom. It will help the bike grip better and help stalling. It also comes with an ignition cover spacer, gasket, and longer ignition cover bolts. You will need to remove 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. Puller not included.