... plating Screw Thread:taptite ISO: ISO9001:2008, ISO14001:2004 Features: Blue zinc plated Hex Head Tapping Screws 1.Material: Mild carbons ... :black oxide,zinc plated(white zinc, black zinc, colour zinc, blue zinc), phophated, plain finish, nickel plated, chromated and etc.3 ... serve for you with the good quality and competitive price. Blue zinc plated Hex Head Tapping Screws