The ball screw is the most commonly used mission elements in tool mechanics and precision mechanics. FUNCTION: The main function of this ball screw is to convert rotational motion into linear motion with high accuracy, reversibility and high efficiency. , resibility and high efficiency. FOR RM1605, SFU1605 BALL SCREW: It fits for RM1605, SFU1605 Ball Screw, easy and quick to install without much effort. Model:SFU2005 Hole Diameter: 20mm Material:steel colour:Silver Package Contents: 1 * Ball Nut+Ball Screw Rod Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.