After the upgrade advantage:1, Reduce the radiator length, thickness and diameter (shorter lengths help to increase the stability of the hot end), while increasing the number of heat sink, making the heat end while reducing weight, have better thermal performance and stability .2, Change the bulky external rotation pneumatic fittings for the catheter cards further reduce weight and reduce the hot end length, but also to the feed deeper, feeding more powerful (pneumatic connectors can only be inserted a short feed pipe, is easily lead feed is not smooth and so on).3, To improve the original heating block, look more simple and practical. Heating pipe, thermistor and aluminum block are fuller contact, so that the temperature control is more precise outstanding.Optional: Long distance 1.75mm, Short distance 1.75mm (Please select the size you need, if you don't understand, please reference pictures)Note: The fan color is random delivery.The thread of the nozzle: M6 threadPackage includes:1 x 3D Printer Extrusion 0.3mm Head Nozzle With Fan