... ,large gear grinder 4,for concrete,terrazzo,epoxy floor grinder heavy duty is not only grinding and polishing concrete, marble,granite, terrazzo ... , but also for repairing, grinding, polishing, crystallizing millstones.floor grinder heavy duty HWG 70 has the quickest motor speed, from 300 rpm ... ;2,All gear box and motor is made of Aluminum alloy,which is strong and durable;3,NSK bearing. It has ...