... .Bit has good guidance Materials of PDC Drag Type Bit 1, Senior tungsten carbide do tire body ... life.Main features and functions of PDC Drag Type Bit 1, bit long life: to diamond ... the PDC Drag Type Bit is suitable for carbonate, limestone, chalk rock, clay rock, siltstone, sandstone and soft, ... effect is particularly significant.Advantages of PDC Drag Type Bit 1.Quickly drill speed , long service life ...