... drop center type. 2.Premium quality nickel-alloy steel 5"high air pressure dth bits 1)Design in the form of ... Mach, Digger etc. Parameter DRILL BITBIT,DIA.(mm)NO.AIR HOLESGAUGE BUTTONSFRONT BUTTONSWEIGHT(kg) DHD13028X16 4X14,3X14 15.0 13328X16 ... .0 QL501302 8X16 7X14 14.5 1332 8X16 7X14 14.5 1402 7X18 7X14 15.5 1462 8X16 8X14 15.6 ... 1522 8X18 8X14 16.5 M501302 8X16 7X14 13.9 1332 8X16 7X14 ...