... Size:various 4.Finish:zinc plated and so on NameSelf Tapping Screw MaterialLow carbon steel,Stainless SteelDiameter3.5 ... plated, yellow zinc plated,plain,HDG,Dacromet,and so onHeadHex washer head,Phillps flat head,Phillips ... metal light compartment and other indoor and outdoor installationAutomobile. carriages, containers, shipbuilding, refrigeration equipments all kinds of Self Drilling Tapping Screws