The AMS 2 Pro Internal Hub Unit is specially designed for Bambu AMS 2 Pro, which is located at the rear of AMS 2 Pro and consisits of four Hall sensors, a magnetic rotary encoder, and a motor. It merges four filament slots into one and used to select particular filaments in AMS 2 Pro and convey filaments from AMS 2 Pro to the printer. The Hall sensor detects when the filament reaches a specific position and activates the brushless motor to provide a additional driving force for feeding the filament.