FYSETC Upgraded Hollow Rail MGN12H/MGN9H 300mm 350mm 400mm Linear Guide Rail Slide Carriage 3D Printer part for Voron 3d Printer About Products: The hollow guide rail is a project that we finalized after extensive testing. Made of stainless steel, the hollow design makes the guide rail lighter and supports high-speed printing. Please note: 1.Preload - represents preloading the slider on the guide rail, and the slider becomes tighter on the guide rail. Preload Z1 represents light preloading, and Preload Z2 represents heavy preloading (if you choose the Preload option, please delay the delivery time 10 days!) No Preload - means that the slider can easily move back and forth on the guide rail 2. We support customization of sizes MGN-C and MGN-H with a length of 100-1000mm. If you need customization, please contact customer service. Thank you for your support! Package List： 1*Hollow Stainless Steel Guide Rail Features： 1.Low noise during operation, smooth and rapid movement. 2.Less wear can maintain accuracy for a long time. 3.lightweight,High positioning accuracy