... advantage:1.rough,fine and finish grinding stone surface2.for machine: manual,multi-heads,automatic machine3.strong grinding ability ... high efficiency.Grits: 50#, 200#, 400# with metallic bonded for rough grindingwhereas the grits of 500#, 1500#, 3000# are ... bonded for fine and finish grinding.manual machineautomatic mahcinemulti-head machine diamond grinding plate with metal body and bonds for granite ...