... ISO9001:2008 2.pioneer plant 3.large diameter 4.oil field,foundation,water well 5.drop center,flat,concave Features ... : 1.applicable hard,very hard and medium soft rock formations. 2.Reliable quality, long service life, rare abnormal ... Shank + Face shape + Carbide button shapeExamples For Ordinary BitsDrop center bit, spherical+ballistic(other designs of faces and inserts are available ...