Smooth Running - Upgrade Single Z-axis structure to a dual Z-axis structure, avoiding backlog of filament thoroughly, which improves stability of 3D printing. Easy Leveling - Both ends of the X axis are raised and lowered synchronously, which reduces difficulty and frequency of bed leveling obviously. Increased Accuracy - Compared with original structure, dual Z-axis kit reduces the layer ripple caused by Z-axis vibration, increasing the printing performance of 3D printer. Stable Performance - Compared with Closed Timing Belt, this 3D printer parts set still retains the design of stepper motor to ensure screw rod smooth operation. Easy Assemble - No need to modify or weld the machine, no need to replace motherboard, this 3D printer accessories kit comes with instructions, could be assemble quickly. Colour: silver + black Material: plastic + stainless steel Package Contents: 1 x 3D printer Z axis upgrade kit 1 x English manual