The MMU3 main plate is an essential part of the MMU3 upgrade, and is not included in the upgrade kit if you are moving up from any of the Mk3 printers. This listing includes two nextruder MMU3 Main Plates printed at .08mm layer height using PC-CF. This ensures the plate can hold up inside the extruder, and is the closest FDM equivalent to Prusa's recommended powder-based printing used for plates directly from their factory. Along with the main plates, this item also includes two of the required O-rings which fit inside the main plate to protect the gears of the Nextruder. This listing is great for anyone who needs a couple of spares, or who needs the last piece for their MMU3 upgrade without costly international shipping.