1.certificated with API and ISO , 2.The only manufacture in Hejian Cangzhou . 3.Be professional in manufacture diamond pdc bit We are Cangzhou Great Drill Co.,LTD ,professional in manufacture matrix body diamond pdc bits and steel body diamond pdc bits .diamond core bit ,Natural diamond core bit ,and impregnated core bit.Our products strictly under ISO 9001:2008 according to API . Feature : ...