This Stainless Steel MK8 Nozzle is a drop-in replacement for OEM Makerbot MK8 nozzles. Thread length is 5mm. The MK8 nozzle represents an improvement over the previously used Mk7 nozzle. The main difference between the MK8 Stepstruder and the MK7 is the ratio of melted to unmelted plastic inside the heated nozzle. You don't want PLA to stay melted for too long, because it will start to degrade, but the MK8 design eliminates that problem. About the same amount of plastic fits into each nozzle, but in the MK8 nozzle, more of that plastic remains solid. That means that any given bit of PLA will spend less time sitting in the heated nozzle in it's liquid state, and won’t have much time to degrade. This nozzle is compatible with the MakerBot Replicator 2, 2X, and 5th Generation Desktop 3D Printers,as well as some other brands of 3D printers as Creality: CR-10 / CR-10 V2 / 10S / S4 / S5 / Ender 2 / Ender 3 / Ender 3 Pro/ Ender 5