... ,W,UN,NPT,ACME,API carbide internal & external threaded insert SIZE RANGES ARE 11ER/16ER/22ER11IR/16IR/22IR etc..Items ... black coating,suitable for processing stainless steel(grooving insert) or universal use(threading insert). LDC shows yellow coating,suitable for processing steel ... , CNC inserts and grooving inserts.The performance of our insert can be as good as Tungaloy and Mitsubishi.Our carbide ...