... range coal mining bits/coal mining cutter teeth/tungsten carbide drill bits/coal bitsProduct description:The coal bits are mainly ... .Dimension: 25, 27, 28, 29, 30, 32, 36, 42 mm.Normal Thread Model: M16*2; M14*1.5, M12*1 ... to customer's points. Colliery Drilling Tools Main Standard(mm)DHLM Thread joint 274417 M14×1.5275417 M12×1.75285420 ... M12×1.75 coal bits/coal mining bits/tungsten carbide drill bit