... tapping screws Carbon steel or stainless steel,Hardened quality Counter sunk head tapping screws Carbon steel or stainless steel, zinc ... tapping screwsMaterial: carton steel sae1008, 1018,1022 or stainless steel 201,304,316Diameter : ST2.5,ST2.9,ST3.5,ST3.9 ... plated, brass plated, black phosphated or plain if sus material Counter Sunk Head Philips Self Tapping Screws