Create a secure base for fasteners in plastic, including brittle 3D printed parts. Press these inserts into straight holes that have been drilled, printed, or molded into plastic. Then, heat them with a soldering tip to melt the surrounding material. As the plastic cools, it fuses to the sharp, diagonal ridges around the inserts, which prevents them from being twisted or pulled out. The interior is fully threaded, so you can access the threads from both sides of a through hole. Also known as Chevron and headed inserts.