Protect your valuable and irreplaceable original crankcases from worn-beyond-repair original cylinders (a.k.a. time bombs). These accurate reproductions are cast from state-of-the-art alloys to modern specs and stand up to all horsepowers you can pack on an IOE lower end. Now you can finally have both that stock factory look and a safe engine. Racers around the globe use them with great success for years. Sold as pairs only.