5/16" post, 8mm cap Black/ steel Double Cap Rivet - 13715B
Amazon.com: CRAFTMEMORE 8mm Cap x 10mm Post Leather Rivet Double Cap Rivets Tubular Metal Rapid Rivet Studs Leather Craft 50 Sets (10 mm Post, Silver) : Arts, Crafts & Sewing
Aluminium Button / Dome Head Solid Rivets 2mm, 3mm, 4mm, 5mm, 6mm, 8mm Metric | eBay
Amazon.com: CRAFTMEMORE 9mm Cap x 8mm Post Leather Rivet Double Cap Rivets Tubular Metal Rapid Rivet Studs Leather Craft 50 Sets (8 mm Post, Gunmetal) : Arts, Crafts & Sewing