seamless pattern with flat pop rivet nut with stainless steel mandrel on black tectured chalk board surface. close up. vertical.

air airtight background black bolt bolted bow box carving chiselling clinch closure collar connection copy detail embossment enclosure engineering fastener grange grey guard hard hardness high horizontal imagery industry inner inside internal left metal nut oblong pack ring riv rivet rivnut rustic screw scrimshaw space span surface technical texture thread top