... rock etc. Including impregnated diamond core bit, surface-set diamond bit, reaming shells, casing bit, casing shoe bit, corelifter, corelifter case, core barrel ... impregnated bits are manufactured to give optimum penetration rates and bit life, which is required to keep the cost of ... series: Z46, Z56, Z66, Z76, Z86, Z101, Z116, Z131, Z146 B series: B36, B46, B56, B66, B76, B86, B101, B116, B131 ...