coal bit 1.used in coal mining,geologic drilling 2.long useful life, high efficiency, wide using range coal mining bits/coal mining cutter teeth/tungsten carbide drill bits/coal bitsProduct description:The coal bits are mainly used in coal and mine drilling, have dry-type & wet-type.Dimension: 25, 27, 28, 29, 30, 32, 36, 42 mm.Normal Thread Model: M16*2; M14*1.5, M12*1.75; M14*1.5; M12*1.75We can ...