This is MK10 style 0.4mm hardened nickel nozzle, 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 average nickel with PTFE codeposit. This coating is also very hard and abrasion resistant. If you are working with abrasive filaments like Carbon Fiber, Aluminates or metal filled, this will greatly improve the life of your nozzle. Available in .2mm .3mm .4mm and .6mm size hole.