Kadrick Threaded Inserts Assortment Kit: Includes 520 pieces of M2 M3, M4, M5 threaded inserts, designed for 3D printing components, metric brass knurled nuts, and heat insertion into plastic parts. Heat Set Insert Tool: Suitable for threaded inserts of M2, M2.5, M3, M4, M5, M6, a soldering iron tip tool for 3D printer users, compatible with 900M/T18/FX-888D irons - press tool for plastic 3D printer components.