This is an all metal hot end upgrade for MK10 style extruders. This upgrade includes a modified thermal barrier tube and modified nozzle. Thermal barrier tube is made from 2 different materials. The lower thermal break is made from stainless steel and the colder upper part is made from aluminium. Stainless steel was used for thermal break because it offers low thermal conductivity and aluminium was used for the upper portion because it has a lot better thermal conductivity, to carry away any heat from the filament. All metal hot end will let you print at much higher temperature then possible with original PTFE lined one. Another benefit of an all metal hot end design is more consistent melt chamber control. During slow extrusion rate, in PTFE lined hot end, transition zone from solid to molten plastic tends to creep upward creating more stringy prints. With all metal design a transition zone is always constant, being located right at the heat break. With fast extrusion rate, PTFE tube doesn't have enough thermal conductivity to properly melt all the plastic coming out. On MK10 extruders that limitation happens around 60 mm/s, depending on nozzle size. All metal hot end solves this problem, plastic is surrounded by thermally conductive nozzle throughout its length. Kit includes 1 nozzle and 1 thermal tube.