Model Specific Size For K2 / K2 Pro / M300 Z Axis 42mm square flange, 45mm stack height, mounting hole spacing matches original Z-axis motor seat directly. Pre-assembled Standard Timing Pulley Finished synchronous gear fixed on motor shaft, matches original belt pitch for smooth power transmission. Complete Set With Matching Mount Screws Pack includes 4pcs fixing bolts together with motor, finish installation without extra fastener purchase. High Torque Anti Lost-step Winding Optimized inner coil delivers stable torque, avoid step loss during long-time frequent up-down movement. Low Noise & Fast Heat Dissipation Structure Compact laminated stator reduces running noise and improves heat emission for long continuous operation. Uniform Rotation Improves Printing Stability Even rotary output prevents bed tilting or shaking to lower layer shifting defects.