This is Micro Swiss nozzle for Robo 3D Printers, M6 thread, 1.75mm Filament, Hexagon style hotend. It is made from a 360 brass base material and plated with TwinClad XT coating. TwinClad XT is a nickel composite coating designed for very low friction. It offers one of the lowest coefficient of friction, better then nickel with PTFE co-deposit. This coating is also very hard and abrasion resistant. 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.