Model H300E Metallographic specimen grinding and polishing machine is equipped with single disc and features stepless speed changing for grinding and polishing. It can finish the whole process of rough grinding, fine grinding, rough polishing and finishing polishing for specimen preparing. By adjusting the transducer, it can realize the rotating speed of grinding and polishing disc adjustable from 50 to 600 rpm. This bring this machine with much more extensive applying and make it become the necessary metallographic specimen preparing instrument for using in factories, scientific research institutes and laboratories of colleges.