The nozzle (PLUS/Large Flow version) is M6 thread 0.4mm with insert is Hardened Steel, DLC Coatings Diamond-Like Carbon, Body is Copper Alloy Nickel Plating for Creality K1 & K1 Max 3D Printers. If you are working with abrasive Carbon Fiber, Stainless Steel, wood filled or any other metal filled filaments, this will greatly improve the life of your nozzle.