... points throughout the life of the bit.) You'll find information about correctly choosing the perform of impregnated diamond core bit for ... to medium abrasive stratum. Recommended to use when stratum''s information is uncertain.B7#,B8# ——applicable to stable,vitreous,low ... to medium abrasive stratum. Recommended to use when stratum''s information is uncertain.C7#,C8# ——applicable to stable,vitreous,low ...