1/4" raw copper nail head rivets. Approx. 1.3mm (16-gauge) diameter, with 3.6mm flat head. These rivets are not made to be used with a screw-down riveting tool. Punch or drill a hole (1.3-1.5mm) into your items, insert rivet, trim wire end to 1/16", and use a ball peen or chasing hammer to flatten wire end. The more pieces you layer, the longer rivet you need.