[Compatible 3D Printers]: This 2pcs extruder hotend replacement kits are only for S1/ S1 Combo FDM 3d printers, not for other 3d printer models. Please confirm your 3d printer model before ordering. [High Quality 3D Printer Accessories]: Includes 1 packs assembled hotend kits parts: high precision nozzle, throat tube, heater block thermistor and heater for smoother printing and better 3D printed models. [Support High Speed Printing]: Semi-assembled hotend with all-metal throat design makes the print head heated evenly and the filament flows smoothly in the throat nozzle to support high speed printing. And produced by a rigorous design and testing team, no leakage and clogging, you can easily start your 3D printing experience. [Warm Note]: We kindly suggest you please check whether each part is tightened before use, because the assemble hotend kit be loosened during transportation. Then after installing this hotend print head kit, we suggest you to re-level the heat bed. It is not