We can customise the linear rail, including the length and finishing. We offer a full range of different diameters of linear rail shaft bars: 5, 6, 8, 10, 12, 13, 14, 16, 20, 25, 30, 35, 40, 50 mm and so on - We can process the end of the rail as you need, some examples you can see the image 4 Please let us know if you require this. 4Pcs Diameter 12mm chrome linear motion rod shaft steel smooth rod L: 33.07 inch / 840mm We could provide all the customization: any length, threading, and other end processing, you could get some information from pic 2, if you have needs, please message us, thank you Adapting 45 high quality steel, high frequency quenching, surface chromium plating (15um-20um). The case hardness could be... Humanization Design: Chamfer on both ends, easier to install linear bearings and won't hurt fingers when installing it Chrome Steel Shaft For CNC 3D Printer Coavoo Linear Rod Shaft 4Pcs 12mm X 840mm, Diameter 12mm Case Hardened DIY 3D Printer Rods The case hardness could be reach to 58-64 HRC., Durable and corrosion-resistant Adapting 45# high quality steel, Good bending resistance, high frequency quenching, surface chromium plating(15um-20um).