... -M20 3)Material: stainless steel 200,304,316 4)grade:A2,A4 DIN1587 FLANGE NUT: Material: carbon steel,stainless steel or ... brass Head: hex,round or square Finish: plain,zp,HDG Material: carbon steel ... ,stainless steel or brassHead: hex,round or squareFinish: plain,zp,HDG ,phosphated,nikel,darcromet,cr3 ...