center drill spot drilling center drill set Row socket drill Super high wear-resistant/high impact-resistantapplication/high ... , thank you! (*^_^*) center drill spot drilling center drill set Row socket drillSuper-hard processing of professional, special, non-standard, special ... general tungsten steel, it has 3~5 times more life time. Conforming to ISO K10~K25/P10~P25.VRA201: Imported ultra ...