... material: steel, 3. finish: zinc non-standard flat head socket rivets with internal thread1.Standards:DIN ,ANSI ... screws, egg neck bolt, fishbolt, countersunk head bolt. Expansion bolt, expansion screw.etc.Specialized ... bolts,screws,studs,nuts,washers,threaded Rods,pins,rivets,stamping,circlips and other nonstandard ... .8.3. Bolt used on guardrail panel of expressway with mechanical property of Grade ...