K800 Magnet Joint Spherical Ball Screw For 3D Printer Accessories 12mm-M4-15mm<br>  <br> Specifications:  <br> Ball diameter: 12mm<br> For : M4<br> Length: 15mm<br>  <br> Package include:  <br> 1  x K800 Magnet Joint Spherical Ball Screw For 3D Printer Accessories 12mm-M4-15mm