alloy drill bushing 1: material:yg6 yg8 yg10 yg15 2: hardness:89-91 3: Can be customize made Tungsten alloy drill bushing 1: material:yg6 yg8 yg10 yg152: hardness:89-913: Can be customize made .................................................................................... Features Recommand Grade:YG6, YG6X, YG8, YB12, YG15 TYPE:S11, S12, S13, S22, S23.S31, also provide costom type. ...